Method of scattering fine spacers method of manufacturing liquid crystal display, apparatus for scattering fine spacers with electrostatic control and confinement, and liquid crystal display

ABSTRACT

The present invention has its object to provide a method of spraying particles by which predetermined quantities of particles can be disposed on specified electrodes, in particular a method of spraying particles by which spacers can be sprayed in interelectrode gaps selectively even in the case of substrates comprising pattern-forming transparent electrodes, such as those used in liquid crystal display devices, and a method of producing liquid crystal display devices of high contrast and high display uniformity by which spacers can be disposed in interelectrode gaps without sacrificing the aperture ratio and by which spacers can be disposed on the substrate without irregularity to attain a uniform cell thickness over the whole substrate, as well as a particle spraying apparatus and a liquid crystal display device. 
     The present invention provides a method of spraying particles 
     which comprises applying a voltage of the same polarity as the particle charge polarity to a plurality of electrodes formed on a substrate 
     and spraying the particles while utilizing the repulsive force operating on the particles, 
     wherein means is employed for preventing the particles from being forced out of the electrode domain comprising the plurality of electrodes.

TECHNICAL FIELD

The present invention relates to a method of spraying particles, amethod for producing a liquid crystal display device, a particle sprayerand a liquid crystal display device.

BACKGROUND ART

With the advancement of electronic technology, particles have been putto wide, practical use in various fields. Among such particles, theremaybe mentioned particles used as spacers in liquid crystal displaydevices, for instance.

In one of the fields of application of such particles, liquid crystaldisplay devices, for instance, are widely used in personal computers,portable electronic apparatus and the like. Generally, a liquid crystaldisplay device comprises, as shown in FIG. 75, a liquid crystal layer 7sandwiched between two paired insulating substrates 1, on which colorfilters 4, a black matrix 5, transparent electrodes 3, an alignmentlayer 9 and so on are formed.

The distance between the above paired insulating substrates 1, namelythe thickness of the liquid crystal layer, influences the transmittanceof light and, therefore, if the liquid crystal layer thickness is notmaintained constant all over the display area of a liquid crystaldisplay device, satisfactory display will not be attained. For thisreason, spacers 8, for example glass fibers or truly spherical plasticbeads, are disposed between the paired insulating substrates so that theliquid crystal layer thickness may be maintained constant all over thedisplay area.

These spacers are dispersed uniformly on the alignment layer, forexample, by spraying, together with a compressed gas, from a nozzle (dryspraying) or spraying of a liquid composed of spacers and a volatileliquid (wet spraying) after alignment layer formation. Thereafter, theinsulating substrate is paired with a counterpart insulating substratefor panel alignment and a liquid crystal, for example a nematic liquidcrystal, is filled into the space between the paired insulatingsubstrates with spacers sandwiched therebetween.

When, however, spacers are disposed also on pixel electrodes within thedisplay area, light leakage occurs from such spacers and the substantialaperture ratio is thereby reduced, so that such problems as displayunevenness and reduced contrast arise.

For solving such problems as mentioned above, it is only necessary todispose spacers only in those electrode gaps which are nondisplay areas,namely only at sites of a black matrix, which is constituted of a lightshield layer. The black matrix is provided for the purpose of improvingthe display contrast of the liquid crystal display device and, in thecase of TFT type liquid crystal display devices, for the purpose ofpreventing their elements from erroneously operating in response toexternal light.

For TFT type liquid crystal display devices, a technology of disposingspacers at sites corresponding to the black matrix, namely at sitesother than display pixel sites, is disclosed in Japanese KokaiPublication Hei-04-256925 which comprises maintaining the gate electrodeand drain electrode at the same electric potential in the step ofspraying spacers. Further, Japanese Kokai Publication Hei-05-61052discloses a method comprising applying a positive voltage to the circuitelectrodes and charging spacers negatively and spraying them by drymethod. In these technologies, it is intended to control spacerdisposition by applying a voltage to electrodes formed on the substrate.

However, they have a problem. Namely, application of a voltage to thesubstrate having thin film transistors (TFTs) formed thereon, for thepurpose of controlling the spacer disposition, may lead to destructionof elements by that voltage, hence to failure to function as a liquidcrystal display device.

There is another problem. Namely, such technologies as mentioned abovecannot be employed in STN (supertwisted nematic) type liquid displaydevices since the sites corresponding to the black matrix are spacesamong transparent electrodes.

On the other hand, as a technology of disposing spacers in spacesbetween stripe-form transparent electrodes constituted by disposing aplurality of linear transparent electrodes in parallel on a substrate,as in STN type liquid crystal display devices, there are disclosed, inJapanese Kokai Publication Hei-03-293328 and Japanese Kokai PublicationHei-04-204417, methods of producing liquid crystal display devices whichcomprise charging spacers either positively or negatively and applying avoltage of the same polarity to the transparent electrodes on thesubstrate in the step of spacer spraying.

In particular, according to Japanese Kokai Publication Hei-04-204417, aconductor is disposed below the electrode substrate in a spacer sprayerfor positive voltage application so that the velocity of falling ofnegatively charged spacers may be controlled. It is further disclosedthat, for avoiding adhesion of negatively charged spacer particles tothe wall of the spray chamber, the chamber should be made of a conductorto enable negative voltage application.

However, when, in practicing these methods, the spacer charge amountand/or the voltage to be applied to electrodes is selected at a lowlevel (voltage value: not higher than about 1,000 V), the repulsiveforce (repellent force) between spacers and electrodes becomes weak, andthe force for shifting spacers to interelectrode spaces becomesinsufficient, hence the selectivity toward spacer disposition inelectrode-free areas (interelectrode areas) becomes poor, with theresult that a number of spacers are disposed also on each electrode, asshown in FIG. 76.

Conversely when the spacer charge amount and/or the voltage to beapplied to electrodes is increased (voltage value: about severalkilovolts), the repulsive force between spacers and electrodes becomesstrong and the selectivity toward spacer disposition in electrode-freeareas (interelectrode areas) is improved, as shown in FIG. 77.

In this case, however, the repulsive force acts more strongly over theset of electrodes, so that the tendency of spacers to be turned out ofthe domain of the electrodes increases; as a result, no spacers aredisposed at all in the peripheral region of the electrode domain, hencethe cell thickness cannot be controlled in the peripheral region of theelectrode domain. Although such phenomenon occurs already at a state atwhich the repulsive force is still weak, the area of spacer-freeportions unfavorably and markedly increases as the repulsive forceincreases.

In Japanese Kokai Publication Hei-08-76132, there is disclosed a methodof disposing spacers more selectively as compared with the methodsmentioned above. The method comprises charging spacers to be sprayedeither positively or negatively, applying a voltage opposite in polarityof the spacer charge to first electrodes provided in areas on theinsulating substrate where spacers are to be disposed, and applying avoltage of the same polarity as the spacer charge polarity to secondelectrodes provided in areas on the insulating substrate where nospacers are to be disposed, to thereby apply a repulsive force and anattractive force between spacers and the electrodes so that the spacersmay be disposed either on the first electrodes or on the secondelectrodes with good selectivity.

This method, however, has a problem in that the contrast is decreased bythe occurrence of spacers on the electrodes. Another problem is thatwhen this method is applied to the production of simple matrix typeliquid crystal display devices, it is necessary to form electrodes forspacer disposition in addition to the pixel electrodes and the apertureratio decreases accordingly.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to solve the aboveproblems and provide a method of spraying particles by whichpredetermined quantities of particles can be disposed on specifiedelectrodes, in particular a method of spraying particles by whichspacers can be sprayed in interelectrode gaps selectively even in thecase of substrates comprising pattern-forming transparent electrodes,such as those used in liquid crystal display devices, and a method ofproducing liquid crystal display devices of high contrast and highdisplay uniformity by which spacers can be disposed in interelectrodegaps without sacrificing the aperture ratio and by which spacers can bedisposed on the substrate without irregularity to attain a uniform cellthickness over the whole substrate, as well as a particle sprayingapparatus and a liquid crystal display device.

In a first aspect, the present invention provides a method of sprayingparticles

which comprises applying a voltage of the same polarity as the particlecharge polarity to a plurality of electrodes formed on a substrate

and spraying the particles while utilizing the repulsive force operatingon the particles,

wherein means is employed for preventing the particles from being forcedout of the electrode domain comprising the plurality of electrodes.

In a second aspect, the invention provides a method for producing aliquid crystal display device comprising

spraying spacers onto at least one of a first substrate comprising atleast pattern-forming transparent electrodes and having at least onedisplay area and a second substrate to be disposed opposedly above thefirst substrate

and filling a liquid crystal into the space between both the substrates,

wherein accessory electrodes are provided outside the display area

and, in spraying positively or negatively charged spacers onto thesubstrate, two or more voltages differing in voltage value are appliedto respective transparent electrodes

and a voltage is applied to the accessory electrodes as well to therebycontrol the electric field generated above the transparent electrodesand above the accessory electrodes so as to cause selective spacerdisposition only in a predetermined transparent electrode gap among thegaps between respective neighboring transparent electrodes.

In a third aspect, the invention provides a method for producing aliquid crystal display device comprising

spraying spacers onto at least one of a first substrate comprising atleast pattern-forming transparent electrodes and a dummy electrode and asecond substrate to be disposed opposedly above the first substrate

and filling a liquid crystal into the space between both the substrates,

wherein, in spraying positively or negatively charged spacers onto thesubstrate, two or more voltages differing in voltage value are appliedto respective transparent electrodes and a voltage is applied to thedummy electrode as well,

the predetermined transparent electrode gaps in which spacers are to beselectively disposed are provided between respective two neighboringtransparent electrodes,

the number of transparent electrodes is even,

and the two or more voltages differing in value are applied in a mannersuch that when the spacer charge polarity is positive (+), the lowest ofthe two or more voltages differing in value is applied to the respectivetwo neighboring transparent electrodes between which spacers are to bedisposed in the middle,

and when the spacer charge polarity is negative (−), the highest of thetwo or more voltages differing in value is applied to the respective twoneighboring transparent electrodes between which spacers are to bedisposed in the middle.

In a fourth aspect, the invention provides a method for producing aliquid crystal display device comprising

spraying spacers onto at least one of a first substrate comprising atleast pattern-forming transparent electrodes and a dummy electrode and asecond substrate to be disposed opposedly above the first substrate

and filling a liquid crystal into the space between both the substrates,

wherein, in spraying positively or negatively charged spacers onto thesubstrate, the substrate is disposed in close contact with an earthedconductive stage,

a conductor is provided in a state electrically insulated from theconductive stage,

said conductor being a conductive frame having an opening,

and said conductive frame being disposed on the periphery of thesubstrate with or without partial overlapping with the substrateperiphery,

and wherein a voltage is applied to the transparent electrodes and theconductive frame.

In a fifth aspect, the invention provides a method for producing aliquid crystal display device comprising

spraying spacers onto at least one of a first substrate comprising atleast pattern-forming transparent electrodes and an alignment layer andhaving at least one display area and a second substrate to be disposedopposedly above the first substrate

and filling a liquid crystal into the space between both the substrates,

wherein, in spraying positively or negatively charged spacers onto thesubstrate, the substrate is disposed in close contact with an earthedconductive stage,

a voltage having the same polarity as the spacer charge polarity isapplied to the transparent electrodes on the substrate,

a conductor is provided, outside the display area, in a stateelectrically isolated from the conductive stage

and a voltage having the same polarity as the polarity of the voltageapplied to the transparent electrodes is applied to the conductor tothereby form almost the same electric field within and without thesubstrate.

In a sixth aspect, the invention provides a method for producing aliquid crystal display device comprising

spraying spacers onto at least one of a first substrate comprising atleast pattern-forming transparent electrodes and an alignment layer andhaving one or more display areas and a second substrate to be disposedopposedly above the first substrate

and filling a liquid crystal into the space between both the substrates,

wherein, in spraying positively or negatively charged spacers onto thesubstrate, the substrate is disposed in close contact with an earthedconductive stage smaller in size than the substrate to allow thesubstrate periphery to be apart from the conductive stage

and a voltage of the same polarity as the spacer charge polarity isapplied to the transparent electrodes on the substrate.

In a seventh aspect, the invention provides a particle sprayer fordisposing charged particles selectively on a substrate having aplurality of electrodes

which comprises a nozzle for spraying charged particles onto thesubstrate,

a conductive stage having a fixed position and serving to hold thesubstrate onto which charged particles are to be sprayed,

a plurality of push-up pins for mounting the substrate on anddismounting the substrate from the conductive stage,

a probe for applying a voltage identical in polarity with the chargedparticles to a plurality of electrodes on the substrate disposed on theconductive stage,

and a conductor being electrically insulated from the conductive stage,

said conductor being a conductive frame provided with an opening smallerin size than the substrate,

and said conductive frame being disposed on the top of the substratedisposed on the conductive stage and being applied a voltage of the samepolarity as the charged particle polarity thereto.

In an eighth aspect, the invention provides a liquid crystal displaydevice as obtainable by utilizing the method of spraying particlesaccording to the first aspect of the invention.

In a ninth aspect, the invention provides a liquid crystal displaydevice as obtainable by the method for producing a liquid crystaldisplay device according to the second or third aspect of the invention.

In a tenth aspect, the invention provides a liquid crystal displaydevice as obtainable by the method for producing a liquid crystaldisplay device according to the fourth, fifth or sixth aspect of theinvention using the particle sprayer according to the seventh aspect ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view illustrating an equipotentialsurface above the substrate in the prior art method for producing aliquid crystal display device.

FIG. 2 is a schematic plan view illustrating the relation between thetransparent electrodes and dummy electrode formed on the substrate, asseen from above, in the method for producing a liquid crystal displaydevice according to the present invention, wherein the dummy electrodeis connected with the transparent electrodes.

FIG. 3 is a schematic plan view illustrating the relation between thetransparent electrodes and dummy electrode, as seen from above, in themethod for producing a liquid crystal display device according to thepresent invention, wherein the dummy electrode is not connected with thetransparent electrodes.

FIG. 4 is a schematic sectional view illustrating a spacer sprayer to beused in the practice of the present invention.

FIG. 5 is a sectional view illustrating an electrode pattern relevant tothe present invention.

FIG. 6 is a schematic view illustrating the manner of spacer dispositionas attainable according to the present invention.

FIG. 7 is a schematic view illustrating the method of disposing spacersby means of a macroscopic electric field according to the presentinvention.

FIG. 8 is a schematic view illustrating the conventional method ofdisposing spacers by means of a macroscopic electric field.

FIG. 9 is a schematic view illustrating the regions relatively high involtage (+ (positive)) and the regions relatively low in voltage (−(negative)) formed above stripe-shaped transparent electrodes, as seenfrom above the stripe-shaped transparent electrodes.

FIG. 10 is a schematic view illustrating a trouble encountered when thepolarity of the voltage applied to the transparent electrodes is reverseto the spacer charge polarity.

FIG. 11 is a plan view illustrating the electrode pattern in anembodiment of the present invention.

FIG. 12 is a plan view illustrating the electrode pattern in anotherembodiment of the present invention.

FIG. 13 is a plan view illustrating the electrode pattern on one of apair of insulating substrates in producing two liquid crystal displaydevices from the pair of insulating substrates in an embodiment of thepresent invention.

FIG. 14 is a schematic view illustrating the method of disposing spacersby means of an electric field in the middle of the display area in anembodiment of the present invention.

FIG. 15 is a schematic view illustrating the method of disposing spacersby means of an electric field in the vicinity of the periphery of thedisplay area in an embodiment of the present invention.

FIG. 16 is a schematic view illustrating how spacers move under theinfluence of an electric field all over the whole display area in anembodiment of the present invention.

FIG. 17 is a plan view illustrating the electrode pattern on one of apair of insulating substrates in producing two liquid crystal displaydevices from the pair of insulating substrates in an embodiment of thepresent invention.

FIG. 18 is a schematic view illustrating the method of disposing spacersby means of an electric field in the central portion of the display areain an embodiment of the present invention.

FIG. 19 is a schematic view illustrating the method of disposing spacersby means of an electric field in the vicinity of the periphery of thedisplay area in an embodiment of the present invention.

FIG. 20 is a schematic view illustrating how spacers move under theinfluence of an electric field all over the whole display area in anembodiment of the present invention.

FIG. 21 is a schematic view illustrating the method of disposing spacersby means of an electric field in the central portion of the display areain an embodiment of the present invention.

FIG. 22 is a schematic view illustrating the method of disposing spacersby means of an electric field in the vicinity of the periphery of thedisplay area in an embodiment of the present invention.

FIG. 23 is a schematic view illustrating how spacers move under theinfluence of an electric field all over the whole display area in anembodiment of the present invention.

FIG. 24 is a schematic view illustrating the method of disposing spacersby means of an electric field in the central portion of the display areain an embodiment of the present invention.

FIG. 25 is a schematic view illustrating the method of disposing spacersby means of an electric field in the vicinity of the periphery of thedisplay area in an embodiment of the present invention.

FIG. 26 is a schematic view illustrating how spacers move under theinfluence of an electric field all over the whole display area in anembodiment of the present invention.

FIG. 27 is a plan view illustrating the electrode pattern in anembodiment of the present invention.

FIG. 28 is a plan view illustrating the electrode pattern on one of apair of insulating substrates in producing two liquid crystal displaydevices from the pair of insulating substrates in an embodiment of thepresent invention.

FIG. 29 is a schematic view illustrating the method of disposing spacersby means of an electric field in the central portion of the display areain an embodiment of the present invention.

FIG. 30 is a schematic view illustrating the method of disposing spacersby means of an electric field in the vicinity of the periphery of thedisplay area in an embodiment of the present invention.

FIG. 31 is a schematic view illustrating how spacers move under theinfluence of an electric field all over the whole display area in anembodiment of the present invention.

FIG. 32 is a plan view illustrating the electrode pattern in anembodiment of the present invention.

FIG. 33 is a schematic view illustrating the method of disposing spacersby means of an electric field in the central portion of the display areain an embodiment of the present invention.

FIG. 34 is a schematic view illustrating the method of disposing spacersby means of an electric field in the vicinity of the periphery of thedisplay area in an embodiment of the present invention.

FIG. 35 is a schematic view illustrating how spacers move under theinfluence of an electric field all over the whole display area in anembodiment of the present invention.

FIG. 36 is a schematic view illustrating the method of disposing spacersby means of an electric field in the central portion of the display areain an embodiment of the present invention.

FIG. 37 is a schematic view illustrating the method of disposing spacersby means of an electric field in the vicinity of the periphery of thedisplay area in an embodiment of the present invention.

FIG. 38 is a schematic view illustrating how spacers move under theinfluence of an electric field all over the whole display area in anembodiment of the present invention.

FIG. 39 is a schematic view illustrating the high and low voltage statesin the practice of the present invention.

FIG. 40 is a schematic view illustrating a trouble resulting from spacermovements caused by an electric field all over the display area in theprior art.

FIG. 41 is a schematic view illustrating a trouble resulting from spacermovements caused by an electric field all over the display area in theprior art.

FIG. 42 is a schematic view of a comb-shaped electrode to be used in anembodiment of the method for producing a liquid crystal display deviceaccording to the present invention.

FIG. 43 is a schematic view illustrating the method for producing aliquid crystal display device according to the present invention.

FIG. 44 is a schematic view of a substrate provided with dummyelectrodes which is to be used in an embodiment of the method forproducing a liquid crystal display device according to the presentinvention.

FIG. 45 is a schematic view of a substrate provided with dummyelectrodes which is to be used in an embodiment of the method forproducing a liquid crystal display device according to the presentinvention.

FIG. 46 is a schematic view illustrating the relation among the firstsubstrates, stage and conductive frame in an embodiment of the methodfor producing a liquid crystal display device according to the presentinvention, the top figure being a plan view seen from above and thebottom being a sectional view.

FIG. 47 is a schematic view illustrating the relation among the firstsubstrates, stage and conductive frame in an embodiment of the methodfor producing a liquid crystal display device according to the presentinvention, the top figure being a plan view seen from above and thebottom being a sectional view.

FIG. 48 is a schematic side view illustrating how spacers are sprayedonto the first substrate in an embodiment of the method for producing aliquid crystal display device according to the present invention.

FIG. 49 is a schematic sectional view illustrating a method of applyinga voltage from the conductive frame to the dummy electrode in anembodiment of the method for producing a liquid crystal display deviceaccording to the present invention, wherein a needle terminal (probe)projects out from a flat surface facing the substrate on the conductiveframe to the dummy electrode for voltage application and wherein theneedle terminal (probe) is provided on the connecting plane connectingthe conductive frame with the dummy electrode.

FIG. 50 is a schematic sectional view illustrating a method of applyinga voltage from the conductive frame to the dummy electrode in anembodiment of the method for producing a liquid crystal display deviceaccording to the present invention, wherein a needle terminal (probe)projects out from a flat surface facing the substrate on the conductiveframe to the dummy electrode for voltage application and wherein theneedle terminal (probe) has a certain length and connects a side of theconductive frame and a side of the dummy electrode.

FIG. 51 is a schematic side view illustrating how spacers are sprayedonto the first substrate in an embodiment of the method for producing aliquid crystal display device according to the present invention.

FIG. 52 is a schematic sectional view illustrating the equipotentialsurface over the substrate when the stage is not earthed.

FIG. 53 is a schematic sectional view illustrating the equipotentialsurface over the substrate in the method for producing a liquid crystaldisplay device according to the present invention.

FIG. 54 is a schematic sectional view illustrating the equipotentialsurface over the substrate in the method for producing a liquid crystaldisplay device according to the present invention.

FIG. 55 is a schematic view, inclusive of a plan view and sectionalviews, illustrating the relation between the substrate and theconductive frame in the method for producing a liquid crystal displaydevice according to the present invention.

FIG. 56 is a schematic sectional view illustrating the case where theconductive stage and conductive frame are formed in isolation from eachother on an insulator in practicing the method for producing a liquidcrystal display device according to the present invention.

FIG. 57 is a schematic sectional view illustrating the relation betweenthe conductive stage and conductive frame in the method for producing aliquid crystal display device according to the present invention, with asubstrate end portion being shown on exaggerated scale.

FIG. 58 is a schematic sectional view illustrating the relation betweenthe conductive stage and conductive frame in the method for producing aliquid crystal display device according to the present invention, with asubstrate end portion being shown on exaggerated scale.

FIG. 59 is a schematic view, inclusive of a plan view and a sectionalview, illustrating the picture frame-like state of the black matrix inthe method for producing a liquid crystal display device according tothe present invention.

FIG. 60 is a schematic sectional view illustrating the relation betweenthe conductive stage and conductive frame in the method for producing aliquid crystal display device according to the present invention, with asubstrate end portion being shown on exaggerated scale.

FIG. 61 is a schematic sectional view illustrating the relation betweenthe substrate and stage in the prior art method for producing a liquidcrystal display device.

FIG. 62 is a schematic sectional view illustrating the relation betweenthe substrate and stage in the method for producing a liquid crystaldisplay device according to the present invention.

FIG. 63 is a schematic sectional view illustrating the equipotentialsurface over the substrate in the method for producing a liquid crystaldisplay device according to the present invention.

FIG. 64 is a schematic sectional view illustrating an example of theparticle sprayer according to the present invention.

FIG. 65 is a schematic sectional view illustrating the feeding andcarrying-out of the substrate in the sprayer shown in FIG. 64.

FIG. 66 is a schematic sectional view illustrating, on exaggeratedscale, the essential elements shown in FIG. 64.

FIG. 67 is a schematic plan view illustrating the relation between thesubstrate and conductive frame in the particle sprayer according to thepresent invention.

FIG. 68 is an explanatory drawing showing an equipotential lineobtainable upon application of a voltage to the conductive frame and tothe transparent electrodes in the particle sprayer according to thepresent invention.

FIG. 69 is a plan view showing the electrodes on the insulatingsubstrate in an embodiment of the present invention.

FIG. 70 is a schematic sectional view showing a liquid crystal displaydevice according to the present invention.

FIG. 71 is a schematic view illustrating the method for producing aliquid crystal display device according to the present invention.

FIG. 72 is a schematic sectional view illustrating a method of voltageapplication to the dummy electrode in an embodiment of the method forproducing a liquid crystal display device according to the presentinvention.

FIG. 73 is a schematic sectional view of the spacer sprayer used in anembodiment of the method for producing a liquid crystal display deviceaccording to the present invention.

FIG. 74 is a schematic sectional view of the spacer sprayer used inanother embodiment of the method for producing a liquid crystal displaydevice according to the present invention.

FIG. 75 is a schematic sectional view of a prior art liquid crystaldisplay device.

FIG. 76 is a schematic view illustrating the prior art spacerdisposition characteristics.

FIG. 77 is a schematic view illustrating the prior art spacerdisposition characteristics.

EXPLANATION OF CODES

1—insulating substrate (glass substrate)

2—polarizer

3, 3 a, 3 b—display electrode (linear transparent electrode, pixelelectrode)

4—color filter layer

5—conductive black matrix

6—overcoat layer

7—liquid crystal

8—spacer

9—alignment layer

10—chamber (sprayer itself)

10 a—cover

11 a—nozzle

11 b—particle tank

12—voltage application apparatus (direct current source)

13—spacer metering (dosing) feeder

14—insulator

15—conductive stage (stage, electrode)

16—parting line

17—pipeline (spacer blowing out tube)

18, 18 a, 18 b—conductor

19—conducting part

19 a—conducting wire (A)

19 b—conducting wire (B)

20, 20 a, 20 b—auxiliary electrode

21—dummy electrode

22—display electrode area

23—insulation layer

24—sealing material

25—spacer within sealing

26—black matrix picture frame

27—transparent conductive layer

28—dummy electrode area

29, 29 a, 29 b—accessory electrode

30—display area

31—driving mechanism

32—robot mechanism

32 a—arm

32 b—sucking cup

33—spacer spraying range

34—conductive frame (field, repulsive force field)

34 a—opening

34 b—push-up shaft

35—probe (needle terminal)

36—push-up pin

37—equipotential line (equipotential surface)

DISCLOSURE OF THE INVENTION

In the following, the present invention is described in detail.

The method of spraying particles according to the first aspect of thepresent invention comprises applying a voltage of the same polarity asthe particle charge polarity to a plurality of electrodes formed on asubstrate and spraying the particles while utilizing the repulsive forceoperating thereon,

wherein means is employed for preventing the particles from being turnedout of the electrode domain comprising the plurality of electrodes.

The above substrate may be made of glass, a resin, a metal or any otherappropriate material and has a plurality of electrodes on its surface.Its shape is not particularly restricted; thus, it may be substrate-likeor film-shaped, for instance. When a metal substrate is used, however,it is necessary to provide an insulating layer on the metal substrate toprevent the electrodes formed on its surface from short-circuiting.

The above electrodes include, but are not limited to, transparentelectrodes, linearized transparent electrodes (linear transparentelectrodes) and so on. As the substrate on which the above plurality ofelectrodes are formed, there may be mentioned substrates comprisingpattern-forming transparent electrodes, among others. The abovesubstrate comprising pattern-forming transparent electrodes is, forexample, a substrate having stripe electrodes constituted from lineartransparent electrodes disposed in parallel. The stripe electrodes areused as the so-called display electrodes in liquid crystal displaydevices. The electrode region comprising the above plurality ofelectrodes is the region where the plurality of electrodes form aelectrodes group and, when the plurality of electrodes are used asdisplay electrodes, the region is the display electrode area. In liquidcrystal display devices, the region for performing displaying out of theabove display electrode-forming region is called display area.

In cases where the above method of spraying particles is used in theproduction of liquid crystal display devices, the above substrateincludes, among others, color filter substrates having a black matrix,color filters, an overcoat layer, pattern-forming transparent electrodesand an alignment layer, and substrates having a black matrix, anovercoat layer, pattern-forming transparent electrodes and an alignmentlayer. The substrate onto which spacers are to be sprayed may be asubstrate having a color filter or a substrate to face such substrate asmentioned above.

Therefore, when the above method of spraying particles is applied to theproduction of STN type liquid crystal display devices, the method isapplicable to any substrate, whether it is a common electrode (scanningelectrode) substrate or a segment electrode (display electrode)substrate, on condition that it has pattern-forming transparentelectrodes at the least.

The particles are not particularly restricted but include, for example,metal particles; synthetic resin particles; inorganic particles;light-shielding particles of a synthetic resin containing a pigmentdispersed therein; particles colored with a dye; particles exhibitingadhesiveness upon application of heat or light, for instance; andparticles derived from metal particles, synthetic resin particles,inorganic particles or the like by plating the surface thereof with ametal. They are generally used as spacers in liquid crystal displaydevices. The spacers serve to adjust the cell thickness in liquidcrystal display devices.

The above method of spraying particles may be dry method or wet method.In the wet spraying method, particles are sprayed in the form of adispersion in a mixed solvent composed of water and an alcohol, forinstance. Even in this case, the particles can be charged and,therefore, the effects of the first aspect of the invention will not bereduced. The dry method of spraying is proffered, however, since theamount of charge can be stabilized in the dry spraying.

In the above dry method of spraying, the particles can be charged, forexample, by repetitions of their contacting with a pipeline or byapplication a voltage thereto. Among these, the method comprisingpassing particles through a pipeline by means of such a medium ascompressed air or compressed nitrogen can charge the particles in astable manner. In that case, the moisture content in the medium gasshould preferably be as low as possible from the viewpoint of particlecharging and preventing moisture adhesion to the substrate.

The material of the pipeline may be a metal or a resin and canadequately be selected in connection with the particle charge polarityand the amount of charge.

The metallic pipeline includes, but is not particularly limited to,pipelines made of a single material such as nickel, copper, aluminum ortitanium; and pipelines made of an alloy such as stainless steel, amongothers. It may be a pipeline having a metallic coating, such as a goldor chromium coating, formed by plating, for instance, on the pipelineinside wall.

The resin-made pipeline includes, but is not particularly limited to,pipelines made of Teflon, a vinyl chloride resin, nylon or the like. Forattaining stable charging, however, it is necessary to coat such a resinpipeline with a metal and thereby earth the pipeline. This is because ifthe pipeline is not earthed, the resin pipeline will have an accumulatedcharge, which makes it impossible to attain stable charging, sinceelectric charge exchanging occurs as a result of contacting of theparticles with the pipeline.

For adjusting the amount of charge on the particles, a plurality of suchpipelines differing in material may be connected in series.

When, in spraying particles, the particle charge polarity is the same asthat of the voltage applied to the plurality of electrodes on thesubstrate, for example when the particle charge polarity is positive (+)and the voltage applied to the plurality of electrodes is also positive(+), then the total number of particles sprayed onto the substratebecomes smaller and more stable than the case of omitting the voltageapplication to the plurality of electrodes.

In the peripheral portions of the substrate where the plurality ofelectrodes are absent, however, no repulsive force operates and thoseparticles in the vicinity of the periphery of the substrate are expelledout of the substrate. As a result, the number of particles in portionsaround the region comprising the plurality of electrodes becomesinsufficient. If such technique is applied in the production of liquidcrystal display devices using spacers as the particles, the cellthickness will become reduced in such portions of the device asmentioned above and this may possibly lead to occurrence of displayunevenness.

In that case, a step of imposing a certain load on liquid crystaldisplay devices is included in the process of liquid crystal displaydevice production. If some or other portions of the substrate show anirregular or fluctuating number of spacers, the load per spacer variesand the spacer distortion varies accordingly, hence the cell thicknessvaries, in those portions, possibly leading to uneven display on theliquid crystal display devices.

The cause of such increase or decrease in the number of particles in thevicinity of the periphery of the region comprising a plurality ofelectrodes may be explained for the case of liquid crystal displaydevice production, as follows. As shown in FIG. 1, when spacers areintended to be disposed in transparent electrode gaps by applying avoltage of the same polarity as the spacer charge polarity to thepattern-forming transparent electrodes, a force (repulsive force)repelling falling spacers out of the display area from within thedisplay area operates and, in particular in the vicinity of theperiphery of the display area, there is no repulsive force above thesubstrate region outside the region comprising the plurality oftransparent electrodes and therefore particles to be disposed in theperipheral portions of the display area escape to the outside or, whenthe region outside the display area is wide and large, those particlesare sprayed concentratedly onto the region outside the display area.

Accordingly, the method of spraying particles according to the firstaspect of the invention comprises

applying a voltage of the same polarity as the particle charge polarityto a plurality of electrodes formed on a substrate

and spraying the particles while utilizing the repulsive force operatingon the particles,

wherein means is employed for preventing the particles from being turnedout of the electrode domain comprising the plurality of electrodes.

In particular, even when the amount of particle charge and/or the valueof the voltage to be applied to the plurality of electrodes is increasedfor improving the selectivity of disposition in interelectrode gaps, anaction is produced to prevent particles from being forced out of theelectrode domain comprising the plurality of electrodes, so thatparticles are sprayed and disposed in those interelectrode spaces aswell which occur in the edge portions of the electrode domain comprisingthe plurality of electrodes.

In carrying out the above method of spraying particles, it is preferredthat a dummy electrode be provided outside the electrode domaincomprising a plurality of electrodes and a voltage of the same polarityas the particle charge polarity be applied also to the dummy electrodeto thereby control the electric field above the periphery of theelectrode domain comprising the plurality of electrodes.

Thus, by applying a voltage of the same polarity as the particle chargepolarity to the dummy electrode and adjusting the voltage to therebycontrol the electric field, it becomes possible to cause a repulsiveforce to operate on particles and thus push back those particlesotherwise expelled out of the electrode domain comprising a plurality ofelectrodes to the inside of the electrode domain, with the result thatparticles are sprayed and disposed also in those interelectrode spaceswhich occur in the edge portions of the electrode domain comprising theplurality of electrodes.

Further, if the voltage applied to the dummy electrode is adjustedproperly, it is also possible to control the density of disposedparticles. In other words, it becomes possible to correct macroscopicdeviations in the electric field in the edge portions of the electrodedomain comprising a plurality of electrodes by applying a voltage to thedummy electrode as well.

Furthermore, by adjusting the voltage applied to the dummy electrode, italso becomes possible to intentionally control the number of particlesto be disposed in the edge portions of the electrode domain comprising aplurality of electrodes and, by applying the first aspect of the presentinvention to the production of liquid crystal display devices, itbecomes possible to adjust the cell thickness in the edge portions (inthe vicinity of sealed portions) of the electrode domain comprising aplurality of electrodes.

The dummy electrode includes within the scope thereof, but is notlimited to, conductive electrodes formed and disposed outside theelectrode domain (electrode group) comprising a plurality of electrodes,such as those mentioned below. Any other known appropriate dummyelectrodes may also be used effectively.

In Japanese Kokai Publication Sho-63-266427, there are disclosed dummyelectrodes which have the same state as in the display electrode-formingparts and are provided for the purpose of improving the quality of thedisplay part having the same color as the background color byeliminating color unevenness resulting from gap irregularity between thesubstrates and to which no display voltage is applied.

The dummy electrodes are provided between the stripe-shaped displayelectrodes made of a transparent conductive material such as ITO asprovided on the upper substrate and the sealed portions formed on theperiphery of the upper substrate. The dummy electrodes make the gapsbetween the display part and sealed portions identical in state with thedisplay part.

When they are formed simultaneously with the display electrodes, thedummy electrodes can be made of the same material and can have the samethickness as the display electrodes. However, no display voltage (signalvoltage) is applied to the dummy electrodes. On the lower substrate,like on the upper substrate, dummy electrodes are formed between thedisplay electrodes and sealed portions.

In Japanese Kokai Publication Hei-02-301724, there are disclosedtransparent electrodes (dummy electrodes) provided for the purpose ofenabling the production of liquid crystal panels having a uniform liquidcrystal layer thickness.

Among the dummy electrodes provided on the upper and lower substrates,the dummy electrode provided on the upper substrate faces the dummyelectrode on the lower substrate on the left side and base side of thenondisplay area and, on the upper side, a transparent electrode formingthe display area. Among the nondisplay area, on the right side, a dummyelectrode on the lower substrate faces a transparent electrode on theupper substrate.

Therefore, transparent electrodes face to each other in all parts of thenondisplay area. As a result, a liquid crystal panel having a uniformliquid crystal layer thickness, which is determined by the gap materialdiameter, can be obtained.

In Japanese Kokai Publication Hei-03-260624, there are disclosed dummyelectrodes provided around segment electrodes at a distance of 1 to 5 μmfrom the segment electrodes for the purpose of preventing the generationof static electricity during rubbing treatment in the step of rubbingtreatment, which is to be followed by cutting off the dummy electrodes.

The dummy electrodes are intended to provide liquid crystal deviceshaving high display quality by preventing the alignment layer from beingdisturbed by static electricity in dot matrix type liquid crystaldevices produced by providing segment electrodes and common electrodesderived respectively from transparent electrode layers on a pair ofsubstrates, further providing an alignment layer on each electrode layerand causing a liquid crystal to be sandwiched between the substrates.

Thus, by providing dummy electrodes at sites surrounding the segmentelectrodes on the substrate with a segment electrode-to-dummy electrodedistance of 1 to 5 μm, it is possible to eliminate static electricityemanation between segment electrodes in the step of rubbing. A liquidcrystal display device showing no color irregularity can be obtained bycutting off the dummy electrodes after rubbing treatment.

In Japanese Kokai Publication Hei-06-51332, there is disclosed a dummyelectrode provided in a matrix type liquid crystal display device forthe purpose of eliminating color irregularity at extraction electrodesites outside the pixel region.

The dummy electrode is provided for rendering the thickness of theoutside of the pixel region identical with the liquid crystal layerthickness in the pixel region.

The above dummy electrode may be formed outside the display area on thesubstrate for preventing the alignment layer from being damaged bysparking caused by static electricity in the process for producing STNtype liquid crystal display devices. For example, when two displaysubstrates having stripe-shaped transparent electrodes are to bemanufactured from one substrate, it is provided around each displayarea, as shown in FIG. 2 or FIG. 3. FIG. 2 is for the case of the dummyelectrode being connected with the transparent electrodes and, FIG. 3 isfor the case of the dummy electrode being not connected with them.

The above method of spraying particles is preferably carried out byapplying a voltage of 500 to 8,000 V to the plurality of electrodes.

As a result of the voltage applied being controlled, the repulsive forceoperating between the particles and electrodes increases, theselectivity in particle disposition in electrode gaps is improvedaccordingly, and the particles are sprayed onto the edge portions of theelectrode domain comprising the plurality of electrodes as well withgood disposition characteristics without the particles being expelledout of the electrode domain comprising the plurality of electrodes.

In carrying out the method of spraying particles according to the firstaspect of the invention, a voltage of the same polarity as the particlecharge polarity is preferably applied to an electrode other than theplurality of electrodes which occurs on the substrate and at leastpartly surrounding the electrode domain comprising the plurality ofelectrodes.

The electrode other than the plurality of electrodes, which is the dummyelectrode, is formed on the substrate having the plurality of electrodesformed thereon, and always serves to correct the unbalanced electricfield formed above the substrate by the plurality of electrodes,irrespective of the position of setting of the substrate in the particlesprayer. Since the plurality of electrodes and the dummy electrode areformed on the substrate, it is not necessary to modify the setting ofthe particle sprayer according to the substrate size and/or thedifference in the voltage applied to the electrodes. This is anadvantage from the industrial viewpoint.

In carrying out the method of spraying particles according to the firstaspect of the invention, it is preferred that the electrode other thanthe plurality of electrodes be provided in the peripheral regionexclusive of an auxiliary electrode site for applying a voltage to theplurality of electrodes.

For example, when the plurality of electrodes are stripe-shapedelectrodes, an auxiliary electrode (solid electrode) for applying avoltage to said electrodes is provided at one end or both ends of thestripe-shaped electrodes, and the electric field irregularity iscorrected by the auxiliary electrode (solid electrode). Therefore, themeans for preventing particles from being forced out of the electrodedomain comprising a plurality of electrodes is preferably providedparticularly at a site where there is no auxiliary electrode.

In the method of spraying particles according to the first aspect of theinvention, the electrode other than the plurality of electrodespreferably has an area larger than the area of each of the plurality ofelectrodes.

Thus, when the electrode area is increased, the repulsive forceoperating on particles increases. By selecting a larger dummy electrodearea than that of each of the plurality of electrodes, a greater actionis produced to turn back particles to the electrode domain comprisingthe plurality of electrodes; as a result, particles are more efficientlydisposed also in interelectrode gaps at the edge portions of theelectrode domain comprising the plurality of electrodes.

In carrying out the method of spraying particles according to the firstaspect of the invention, the one and same voltage is preferably appliedto the plurality of electrodes and to the electrode other than theplurality of electrodes.

If, for example, patterning is carried out so as to cause electricshort-circuiting in forming the plurality of electrodes and the dummyelectrode, it is unnecessary to newly provide an electric wire or thelike for applying a voltage to the dummy electrode, and it isunnecessary, too, to newly and separately prepare a means for voltageapplication to the dummy electrode; this is advantageous from theindustrial viewpoint.

In the method of spraying particles according to the first aspect of theinvention, it is preferred that the electrode other than the pluralityof electrodes be a solid electrode provided in the peripheral region ofthe substrate.

Thus, by applying a voltage to the solid electrode (mesh electrode)provided in the peripheral region of the substrate for eliminating theheight difference, it becomes possible to produce the effects of thefirst aspect of the present invention using the conventional designingstandard without increasing the number of steps.

In that case, any electrode, for example a solid, mesh or blockelectrode, may be employed as the electrode for applying a voltage tothe region outside the electrode domain comprising a plurality ofelectrodes.

Referring to FIGS. 4 to 8, typical embodiments of the first aspect ofthe invention are now described.

FIG. 4 is a schematic view showing a spacer sprayer to be used in anembodiment of the first aspect of the present invention. On the top of atightly closed or substantially closed clean vessel 10, there isprovided a nozzle 11 a for spraying charged spacers 8. A feeder (notshown) for feeding spacers 8 and nitrogen gas is connected with thenozzle 11 a via a pipeline 17. Under the vessel 10, there is disposed aninsulating substrate 1 made of glass or the like and having displayelectrodes 3 formed thereon, and there is also provided an electric wire18 for applying a voltage to the display electrodes 3 for electric fieldformation. It is also possible to form an electric field by means of astage (electrode) 15 provided within the spacer sprayer in lieu ofelectric field formation by voltage application to the displayelectrodes 3.

In the production of liquid crystal display devices, the spraying ofspacers 8 is generally carried out by charging an appropriate quantityof spacers by the charging method mentioned above, in this case chargingspacers negatively, and causing them to be sprayed onto the substrate bymeans of compressed air, compressed nitrogen or the like.

FIG. 5 and FIG. 6 each is a schematic view showing an electrode patternrelevant in the first aspect of the invention. As shown in FIG. 5,stripe-shaped display electrodes 3 and dummy electrodes 21, which arepositioned outside the display area and to which a voltage is to beapplied, are formed on an insulating substrate 1. Means (not shown) forvoltage application to the respective electrodes are also provided. Themeans for voltage application may be auxiliary electrodes formed forvoltage application to the display electrodes 3, or voltage applicationto the display electrodes 3 may be directly performed by applying probepins to the respective electrodes.

Since the electrode domain comprising a plurality of electrodes (displayelectrode area) is charged in general (macroscopically) negatively, arepulsive force (solid line) operates against spacers and the spacerstend to move (escape) out of the display electrode area to the outsideregion where there is no electric field. Nevertheless, by applying anegative voltage to the dummy electrodes 21, it is possible, as shown inFIG. 6, to dispose spacers with certainty also in display electrode gapsin the display electrode end portions otherwise causing a tendencytoward spacer escaping.

The solid lines in FIG. 6 schematically show the magnitudes of therepulsive force exerted on spacers in terms of “upwardly convex”semicircles. FIG. 6 shows the manner of shifting and disposition ofcharged spacers to and in repulsive force valleys.

FIG. 7 and FIG. 8 each is a schematic view illustrating how spacers moveunder the influence of a macroscopic electric field formed on theelectrode substrate. The display electrode area is as a whole(macroscopically) charged negatively and therefore, in the case of FIG.8, a repulsive force is exerted on spacers and the spacers tend to beturned out of the display electrode area to the region where no electricfield is formed. Here, by applying a negative voltage to the dummyelectrodes 21, it becomes possible to turn back the spacers and disposethe spacers also in predetermined display electrode gaps in the displayelectrode end portions to thereby maintain the predetermined spacerdensity in the display electrode end portions and in the middle portionsof the display electrodes.

While the method of electric field control mentioned above referring tothe above embodiment is based on the provision of dummy electrodes 21 onthe substrate having display electrodes formed thereon, another methodis also available which comprises applying a voltage to the stage onwhich the substrate having display electrodes formed thereon is fixed orto the wall of the spacer sprayer to thereby produce the same effects.However, when dummy electrodes for controlling the electric field aredisposed on the stage on which the insulating substrate is set, or onthe wall of the particle sprayer, it becomes necessary to position theinsulating substrate at a location equivalent in relation to the dummyelectrodes provided outside the insulating substrate. This isunfavorable from the industrial viewpoint.

When dummy electrodes are provided on the wall of the particle sprayerand when the insulating substrate is a dual panel one from which twoliquid crystal display devices are to be excised, the intended effect isnot produced along the neighboring sides of the two panels.

Furthermore, when dummy electrodes are provided outside the insulatingsubstrate, the distance from the display electrode area increases, henceit becomes necessary to apply, to the dummy electrodes, a voltage muchhigher than the voltage conventionally applied to the electrodes. Thisis unfavorable from the industrial viewpoint.

On the other hand, by controlling the voltage applied to the dummyelectrode according to the first aspect of the invention, it becomespossible to control also the density of spacers disposed in theperipheral portions of the display area and to exactly control thesubstrate cell thickness, which depends on the spacer dispositiondensity.

While the above embodiment is concerned with a simple matrix type liquidcrystal display device, the first aspect of the present invention isapplicable not only to such simple matrix type liquid crystal displaydevice but of course also to such liquid crystal display devices asferroelectric liquid crystal display devices or TFT type liquid crystaldisplay devices.

In producing liquid crystal display devices by applying the method ofspraying particles according to the first aspect of the invention, it ispossible, by applying a voltage to an electrode (dummy electrodes)outside the display area so that a repulsive force may operate onspacers (particles), to form an electric field which pushes backspacers, which tend to move out of the display electrode area, by themacroscopic potential gradient (gradient of magnitude of repulsiveforce) above the periphery of the display electrode area; it is nowpossible to dispose spacers even in interelectrode gaps in the displayelectrode end portions, where spacer disposition is difficult to attain,with a high probability, hence it is possible to provide higher qualityliquid crystal display devices. It is also possible to control thedensity of spacers disposed in the peripheral portions of the displayarea and thus provide liquid crystal display devices still more higherin display quality.

The method for producing a liquid crystal display device according tothe second aspect of the invention comprises

spraying spacers onto at least one of a first substrate comprising atleast pattern-forming transparent electrodes and having a display areaand a second substrate to be disposed opposedly above the firstsubstrate

and filling a liquid crystal into the space between both the substrates,

wherein accessory electrodes are provided outside the display area

and, in spraying positively or negatively charged spacers onto the abovesubstrate, two or more voltages of different levels are applied torespective transparent electrodes,

and a voltage is applied to the accessory electrodes as well to therebycontrol the electric field generated above the transparent electrodes,

and above the accessory electrodes so as to cause selective spacerdisposition only in predetermined transparent electrode gaps among thegaps between respective neighboring transparent electrodes.

The above-mentioned pattern-forming transparent electrodes, substrate,spacers and spacer charging method are the same as explained above inrelation to the first aspect of the invention.

In applying the method for producing a liquid crystal display deviceaccording to the second aspect of the invention to the production of TFTtype liquid crystal display devices, transparent electrode-free areasare formed on the color filter substrate, which is a common electrodesubstrate, by etching or the like at sites just below the black matrixportions and then spacers are disposed on the substrate by the methodfor producing a liquid crystal display device according to the secondaspect of the invention. Although the common electrode substrate in anordinary TFT type liquid crystal display device has a solid electrode,even etched area-carrying transparent electrodes can be driven in thesame manner as in ordinary TFT type liquid crystal display devices byapplying the same voltage to the respective electrodes.

In accordance with the second aspect of the invention, accessoryelectrodes are provided outside the display area and, in sprayingcharged spacers, two or more voltages differing in value are applied therespective transparent electrodes and a voltage is applied to theaccessory electrodes as well to control the electric field generatedabove the transparent electrodes and above the accessory electrodes andthereby control the repulsive force or attractive force exerted oncharged spacers or the repulsive and attractive forces exerted on suchspacers so as to create the trough of a synthetic repulsive force, thecrest of a synthetic attractive force, or the crest of an attractiveforce synthesized from a repulsive force and an attractive force in eachof predetermined transparent electrode gaps among the gaps betweenrespective neighboring transparent electrodes for selective spacerdisposition only in the predetermined transparent electrode gaps.

The voltage to be applied to the electrodes is not particularlyrestricted in kind but, for example, a direct current voltage, a pulsevoltage may properly be used.

The manner of applying the two or more voltages differing in value tothe respective transparent electrodes is based on a certain applicationpattern, such that the places, at which the electric field formed on thebasis of two or more voltages differing in value as applied to therespective transparent electrodes exerts the strongest attractive forceand/or the weakest repulsive force on spacers, correspond to thepositions of the transparent electrode gaps.

The places at which the strongest attractive force is exerted are thoseplaces among the crests of a synthetic attractive force or the crests ofan attractive force synthesized from a repulsive force and an attractiveforce as formed in the predetermined transparent electrode gaps amongthe gaps between respective neighboring transparent electrodes at whichthe attractive force acts most strongly, while the places at which theweakest repulsive force is exterted are those places among the troughsof a synthetic repulsive force or the troughs of a repulsive forcesynthesized from a repulsive force and an attractive force as formed inthe predetermined transparent electrode gaps among the gaps betweenrespective neighboring transparent electrodes at which the repulsiveforce acts most weakly.

Here, when spacers are intended to be disposed in transparent electrodegaps by merely applying a voltage of the same polarity as the spacercharge polarity to the pattern-forming transparent electrodes inspraying spacers, a force (repulsive force) repelling falling spacersfrom the display area to the outside of the display area acts, as shownin FIG. 1, in the substrate end portions where no transparent electrodeexists, as explained in detail hereinabove referring to the first aspectof the invention; in particular, in the vicinity of the periphery of thedisplay area, there is no repulsive force above the substrate outsidethe display area, so that spacers to be disposed in the peripheralportions of the display area escape outside or, when the region outsidethe display area is wide, spacers are sprayed concentratedly in theregion outside the display area, with the result that only aninsufficient number of spacers are present in the peripheral portions ofthe display area, hence the cell thickness of the liquid crystal displaydevice produced becomes reduced in those portions, which may possiblylead to display unevenness or irregular display on the liquid crystaldisplay device.

On the other hand, when an electric field exerting an attractive forceabove the transparent electrodes is utilized, a phenomenon of theelectric field extending to the portions where no electrode existsoccurs, as shown in FIG. 10, since there is an extended electric fieldon the periphery of the substrate. Therefore, when a voltage reverse inpolarity to the spacer charge is applied to the transparent electrodes,an attractive force acts, thus a force drawing sprayed and fallingspacers inwardly from the outside of the display area acts and aphenomenon occurs that the number of spacers increases in the outermostregion larger than the number in the display area.

To prevent the above two phenomena illustrated by FIG. 1 and FIG. 10, avoltage is applied to the accessory electrodes provided outside thedisplay area in accordance with the second aspect of the invention, sothat a repulsive or attractive force can be exerted on spacers fromoutside the display area, whereby spacers can be prevented from goingout of the display area or coming in from outside the display area.

As a result, spacers can be disposed selectively in predeterminedtransparent electrode gaps and the spacer disposition density can becontrolled even in the vicinity of the periphery of the display area asin the central region. Thus, it is possible, in liquid crystal displaydevices, to attain a uniform spacer disposition density within thedisplay area and improve the contrast by preventing light leakage fromspacers without sacrificing the aperture ratio.

Further, when the predetermined transparent electrode gaps in whichspacers are to be selectively disposed are provided between respectiveneighboring transparent electrodes to which the same voltage is applied,the repulsive forces or attractive forces become equalized, saidrepulsive forces or attractive forces being exerted from predeterminedtwo neighboring transparent electrodes upon application of two or morevoltages differing in value to the respective transparent electrodes, oncharged spacers which have moved to the trough of a synthetic repulsiveforce, the crest of a synthetic attractive force or the crest of anattractive force synthesized from a repulsive force and an attractiveforce as exerted on the spacers.

Thus, in cases where repulsive forces act on spacers, the spacers can beselectively disposed in each predetermined transparent electrode gapalone with a good probability in a manner such that they are pushed byequal repulsive forces exerted by the corresponding predetermined twoneighboring transparent electrodes and, in cases where attractive forcesact on spacers, in a manner such that they are attracted by equalattractive forces exerted by the corresponding predetermined twoneighboring transparent electrodes.

Further, when, in cases where spacers are charged positively, thepredetermined transparent electrode gaps in which spacers are to bedisposed selectively are provided between the respective neighboringtransparent electrodes to which the lowest voltage of the two or morevoltages differing in value to be applied to the transparent electrodesis applied and, in cases where spacers are charged negatively, they areprovided between the respective neighboring transparent electrodes towhich the highest voltage of the two or more voltages differing in valueto be applied to the transparent electrodes is applied, the trough of asynthetic repulsive force, the crest of a synthetic attractive force, orthe crest of an attractive force synthesized from a repulsive force andan attractive force can be formed in each predetermined transparentelectrode gap.

Thus, in the case of positively charged spacers, a repulsive force actson them most weakly when the lowest voltage applied to the predeterminedneighboring transparent electrodes is positive and, when the lowestvoltage applied to the predetermined neighboring transparent electrodesis negative, an attractive force acts on them most strongly, so thatthey move to the gaps between those transparent electrodes to which thelowest voltage is applied.

In the case of negatively charged spacers, an attractive force acts onthem most strongly when the highest voltage applied to the predeterminedneighboring transparent electrodes is positive and, when the highestvoltage applied to the predetermined neighboring transparent electrodesis negative, a repulsive force acts on them most weakly, so that theymove to the gaps between those transparent electrodes to which thehighest voltage is applied.

Therefore, spacers can be disposed selectively in the predeterminedtransparent electrode gaps alone with a better probability.

Further, when, in cases where spacers are charged positively, the lowestvoltage is of negative polarity or when, in cases these spacers arecharged negatively, the highest voltage is of positive polarity, spacersmove to the crest of a synthetic attractive force or the crest of anattractive force synthesized from a repulsive force and an attractiveforce generated between the electrodes constituting the predeterminedtransparent electrode gaps, and spacers are further attracted byequalized attractive forces exerted by the two neighboring transparentelectrodes.

Therefore, spacers can be disposed selectively in the predeterminedtransparent electrode gaps alone with a higher probability.

Further, when the voltage or voltages other than the lowest or highestone which are applied to transparent electrodes are of the same polarityas the spacer charge polarity, an attractive force generated between theelectrodes constituting the predetermined transparent electrode gaps andspacers, and a repulsive force generated between other electrodes andspacers act on spacers and the spacers are pushed by the repulsive forcegenerated between other electrodes and spacers, and attracted by theattractive force generated between the predetermined neighboringtransparent electrodes, and thus move toward the crest of an attractiveforce synthesized from the repulsive force and attractive force asformed in each predetermined transparent electrode gap and are furtherattracted by equalized attractive forces exerted from the predeterminedtwo neighboring transparent electrodes.

Therefore, spacers can be disposed selectively in the predeterminedtransparent electrode gaps alone with a higher probability.

When the voltage for charging spacers and the two or more voltagesapplied to the transparent electrodes are of the same polarity, a strongrepulsive force is generated between the other electrode(s) and spacers,and a weak repulsive force is generated between the predeterminedneighboring electrodes and spacers, and the spacers are pushed by thestrong repulsive force generated between them and the otherelectrode(s), and move to the trough of a synthetic repulsive forceexerting between each predetermined transparent gap, and are furtherpushed toward the predetermined transparent electrode gap by therepulsive force, so that the spacers can be disposed selectively in thepredetermined transparent electrode gaps alone with a higherprobability.

In particular, this constitution makes it possible to dispose spacersconcentratedly in the middle of each predetermined transparent electrodegap, since spacers are disposed in the predetermined transparentelectrode gaps in a manner such that they are pushed by a repulsiveforce.

Therefore, the probability of spacers being disposed in edge portions ofthe predetermined neighboring transparent electrodes can be minimized.

In cases where the electric field above the display area as a wholeexerts a repulsive force on spacers, the polarity of the voltage appliedto accessory electrodes is selected so that a repulsive force may beexerted on spacers and, in cases where the electric field above thedisplay area as a whole exerts an attractive force on spacers, thepolarity of the voltage applied to accessory electrodes is selected sothat an attractive force may be exerted on spacers, whereby spacers canbe inhibited from migrating out of the display area by exerting arepulsive force, from outside the display area, on spacers in thevicinity of the edge portions of the display area even when the displayarea as a whole exerts a repulsive force on the spacers and, even whenthe display area as a whole exerts an attractive force on spacers, thespacers occurring outside the display area can be inhibited from cominginto the display area from the outside thereof by exerting an attractiveforce thereon from outside the display area.

Therefore, it is possible to attain a uniform spacer disposition densityeven in the vicinity of the periphery of the display area.

Furthermore, by selecting, as the voltage applied to accessoryelectrodes, the same voltage as that voltage among the two or morevoltages differing in voltage value as applied to the transparentelectrodes, which causes the strongest repulsive force or attractiveforce to exert on spacers, it is possible to exert a sufficientrepulsive or attractive force on spacers to inhibit spacers frommigrating out of and from outside the display area.

Therefore, it is possible to attain a uniform spacer disposition densityeven in the vicinity of the periphery of the display area.

When the above transparent electrodes are stripe-shaped ones, and theaccessory electrodes are disposed along and parallel to the longer sideof the transparent electrodes, the migration of spacers can beeffectively suppressed on both longer sides of the stripe-shapedtransparent electrodes, where, among the four sides forming the displayarea, spacers tend to readily migrate out of the display area or comeinto the display area from the outside.

Therefore, it is possible to attain a uniform spacer disposition densityeven in the vicinity of the periphery of the display area.

Further, by providing the accessory electrodes according to an electrodepattern nearly identical with that of transparent electrodes, it becomespossible not only to form the accessory electrode and transparentelectrodes simultaneously using the same material and thereby simplifythe production process but also to produce the same electric field abovethe outside of the display area as that above the inside of the displayarea and thereby attain a uniform spacer disposition density within thedisplay area.

By utilizing, as the accessory electrodes, those dummy electrodesprovided for reducing the level difference caused by the transparentelectrodes, it is possible to realize the second aspect of the inventionwhile applying the conventional electrode patterns.

Therefore, it is possible to attain a uniform spacer disposition densityeven in the vicinity of the periphery of the display area.

Further, by utilizing, as the accessory electrodes, those dummyelectrodes provided for some other purpose and not applying displayvoltage thereto, it is possible to realize the second aspect of theinvention while utilizing the conventional electrode patterns.

As the above dummy electrodes, there may be mentioned those explainedhereinabove referring to the first aspect of the invention.

Now, referring to FIGS. 11 to 39, typical embodiments of the secondaspect of the invention are described.

In the production of liquid crystal display devices, spacer spraying isgenerally carried out by charging an appropriate quantity of spacers bythe charging method mentioned above, and spraying and disposing themonto the substrate by means of compressed air, compressed nitrogen orthe like, as described referring to the first aspect of the invention.

FIG. 11 and FIG. 12 each is a schematic view showing an electric patternto be applicable in the practice of the second aspect of the invention.As shown in FIG. 11 and FIG. 12, stripe-shaped display electrodes 3 aand 3 b, auxiliary electrodes 20 a and 20 b for applying a voltage tothe display electrodes 3 a and 3 b, respectively, and accessoryelectrodes 29 provided outside the display area are formed on aninsulating substrate 1.

Conductor wires 18, 18 a and 18 b are connected with the auxiliaryelectrodes 20 a and 20 b and accessory electrodes 29 for forming anelectric field by applying voltages to the auxiliary electrodes 20 a and20 b and accessory electrodes 29. Voltages may be applied directly tothe auxiliary electrodes 20 a and 20 b and accessory electrodes 29 bymeans of probe pins or the like without providing the conductor wires18, 18 a and 18 b, or voltages may be applied directly to the displayelectrodes 3 a and 3 b by means of probe pins or the like withoutproviding the auxiliary electrodes 20 a and 20 b.

The display electrodes 3 a occur in pairs of two neighboring displayelectrodes. The display electrodes 3 b occur between a pair of displayelectrodes 3 a and another pair of display electrodes 3 a. In FIG. 11,one display electrode 3 b occurs and, in FIG. 12, two display electrodes3 b occur.

As for the accessory electrodes 29, those dummy electrodes which areformed also in the conventional electrode patterns for reducing thelevel difference caused by the display electrodes and controlling theliquid crystal layer thickness to maintain its uniformity may beutilized as the accessory electrodes 29.

Those dummy electrodes which are formed in the conventional electrodepatterns and to which no display voltage is applied may also serve asthe accessory electrodes 29.

FIG. 13 is a schematic view showing an electrode pattern for oneinsulating substrate in the production of two liquid crystal displaydevices from a pair of insulating substrates in an embodiment of thesecond aspect of the invention. As shown in FIG. 13, the accessoryelectrodes 29 are disposed only in those areas outside each display area30 as seen in the vertical direction of FIG. 13. This is because theauxiliary electrodes 20 a and 20 b are formed in those areas outsideeach display area 30 as seen in the horizontal direction of FIG. 13, andthe auxiliary electrodes 20 a and 20 b produce the same effect as theaccessory electrodes 29. The auxiliary electrodes 20 b and the accessoryelectrodes 29 are connected with each other by conductors, so that thesame voltage is applied to them.

By using such an electrode pattern as shown in FIG. 11 and applyingvoltages differing in voltage value to the auxiliary electrodes 20 a and20 b and the accessory electrodes 29, negative (−) voltages are appliedto the display electrodes 3 a and 3 b and the accessory electrodes 29,wherein the voltage applied to the display electrodes 3 a is relativelyhigher than that applied to the display electrodes 3 b and the accessoryelectrodes 29, as shown in FIGS. 14 to 16. Further, spacers 8 arecharged negatively and then sprayed.

In this way, it is possible to dispose spacers 8 only in each spacebetween the paired display electrodes 3 a in a manner such that spacers8 can be disposed uniformly in spaces between respective paired displayelectrodes 3 a throughout the display area including those spacesbetween respective paired display electrodes 3 a in the vicinity of theedge portions of the display area 30.

Thus, as shown in FIG. 14 and FIG. 15, as the sprayed and fallingspacers 8 approach the display electrodes 3 a and 3 b, repulsive forcesbased on the electric fields generated above the display electrodes 3 aand 3 b and the accessory electrodes 29 act on the spacers 8, and eachspacer goes away from the display electrode 3 b or accessory electrode29 each exerting a strong repulsive force on it, and moves toward thenearest pair of display electrodes 3 a generating a weak repulsiveforce. The spacer 8 that has moved to the display electrodes 3 a ispushed by equal repulsive forces respectively exerted by the twoneighboring display electrodes 3 a, and falls between the displayelectrodes 3 a.

Since the display area 30 as a whole is negatively charged, a repulsiveforce acts on spacers 8 in the vicinity of each edge portion of thedisplay area 30 and tends to move them outside the display area 30, asshown in FIG. 16. This movement of spacers 8 to the outside of thedisplay area 30, however, can be prevented since a voltage capable ofgenerating a strong repulsive force is applied to the accessoryelectrodes 29.

The semicircles in FIG. 14 and FIG. 15 schematically indicate repulsiveforces acting on spacers 8 and the magnitude of each repulsive forceacting on spacers 8 is represented by the size of the semicircle. Thebroken line schematically indicates the synthetic repulsive force actingon spacers 8.

The semiellipses shown in FIG. 16 schematically indicate repulsiveforces acting on spacers 8.

In the above embodiment, spacers 8 fall into each space between twoneighboring display electrodes 3 a while they are pushed by equalrepulsive forces respectively exerted by the display electrodes 3 a, sothat the spacers 8 can be disposed concentratedly in the middle of eachspace between display electrodes 3 a and thus the probability thatspacers 8 may be disposed on edge areas of the display electrodes 3 acan be minimized.

FIG. 17 is a schematic view showing an electrode pattern for oneinsulating substrate in the production of two liquid crystal displaydevices from a pair of insulating substrates in an embodiment of thesecond aspect of the invention. As shown in FIG. 17, the accessoryelectrodes 29 are disposed only in those areas which are outside eachdisplay area 30 as seen in the vertical direction of FIG. 17. This isbecause the auxiliary electrodes 20 a and 20 b are formed in those areaswhich are outside each display area 30 as seen in the horizontaldirection of FIG. 17 and the auxiliary electrodes 20 a and 20 b producethe same effect as the accessory electrodes 29.

By using such an electrode pattern as shown in FIG. 11 and applyingvoltages differing in voltage value to the auxiliary electrodes 20 a and20 b and the accessory electrodes 29, positive (+) voltages are appliedto the display electrodes 3 a and 3 b and the accessory electrodes 29,wherein the voltage applied to the display electrodes 3 a and theaccessory electrodes 29 is relatively higher than that applied to thedisplay electrodes 3 b, as shown in FIGS. 18 to 20. Further, spacers 8are charged negatively and then sprayed.

In this way, it is possible to dispose spacers 8 only in each spacebetween the paired display electrodes 3 a in a manner such that spacers8 can be disposed uniformly in spaces between respective paired displayelectrodes 3 a throughout the display area 30 including those spacesbetween respective paired display electrodes 3 a in the vicinity of theedge portions of the display area 30.

Thus, as shown in FIG. 18 and FIG. 19, as the sprayed and fallingspacers 8 approach the display electrodes 3 a and 3 b, attractive forcesact on the spacers 8, where said attractive forces are exerted by theelectric fields generated above the display electrodes 3 a and 3 b andthe accessory electrodes 29, and each spacer goes away from the displayelectrode 3 b exerting a weak attractive force on it and moves towardthe display electrode 3 a and accessory electrode 29 generating a strongattractive force. The spacer 8 that has moved to the display electrode 3a is attracted by equal attractive forces respectively exerted by thetwo neighboring display electrodes 3 a and falls between the displayelectrodes 3 a.

Since the display area 30 as a whole is positively charged, anattractive force acts on spacers 8 in the vicinity of each edge portionof the display area 30 and tends to move them into the display area 30from outside the display area 30, as shown in FIG. 20. This movement ofspacers 8 from the outside of the display area 30 into the display area30, however, can be prevented, and the density of spacers 8 disposed inrespective spaces between paired display electrodes 3 a can bemaintained at a predetermined level since a voltage capable ofgenerating a strong attractive force is applied to the accessoryelectrodes 29.

The semicircles in FIG. 18 and FIG. 19 schematically indicate attractiveforces acting on spacers 8 and the magnitude of each attractive forceacting on spacers 8 is represented by the size of the semicircle. Thebroken line schematically indicates the synthetic attractive forceacting on spacers 8.

The semiellipses shown in FIG. 20 schematically indicate attractiveforces acting on spacers 8.

By using such an insulating substrate electrode pattern as shown in FIG.17 and applying, according to such an electrode pattern as shown in FIG.12, voltages differing in voltage value to the auxiliary electrodes 20 aand 20 b and the accessory electrodes 29, a positive (+) voltage isapplied to the display electrodes 3 a and a negative (−) voltage to thedisplay electrodes 3 b and the accessory electrodes 29, so that thedisplay area 30 as a whole is charged negatively, as shown in FIGS. 21to 23. Further, spacers 8 are charged negatively and then sprayed.

In this way, it is possible to dispose spacers 8 only in each spacebetween the paired display electrodes 3 a in a manner such that spacers8 can be disposed uniformly in spaces between respective paired displayelectrodes 3 a throughout the display area 30 including those spacesbetween respective paired display electrodes 3 a in the vicinity of theedge portions of the display area 30.

Thus, as shown in FIG. 21 and FIG. 22, as the sprayed and fallingspacers 8 approach the display electrodes 3 a and 3 b, a repulsive forceand an attractive force act on the spacers 8, where both the forces areexerted by the electric fields generated above the display electrodes 3a and 3 b and the accessory electrodes 29 and each spacer goes away fromthe display electrode 3 b or accessory electrode 29 each exerting arepulsive force on it, and moves toward the display electrode 3 agenerating an attractive force. The spacer 8 that has moved to thedisplay electrode 3 a is attracted by equal attractive forcesrespectively exerted by the two neighboring display electrodes 3 a andfalls between the display electrodes 3 a.

Since the display area 30 as a whole is negatively charged, a repulsiveforce acts on spacers 8 in the vicinity of each edge portion of thedisplay area 30, and tends to move them outside the display area 30, asshown in FIG. 23. This movement of spacers 8 to the outside of thedisplay area 30 can be prevented, however, since a voltage capable ofgenerating a repulsive force is applied to the accessory electrodes 29.

The semicircles in FIG. 21 and FIG. 22 schematically indicate repulsiveforces and attractive forces acting on spacers 8 and the magnitude ofeach repulsive force acting on spacers 8 is represented by the size ofthe semicircle convex as seen from above and the magnitude of eachattractive force acting on spacers 8 by the size of the semicircleconvex as seen from below. The broken line schematically indicates thesynthetic repulsive or attractive force acting on spacers 8.

By using such an insulating substrate electrode pattern as shown in FIG.17 and applying, according to such an electrode pattern as shown in FIG.12, voltages differing in voltage value to the auxiliary electrodes 20 aand 20 b and the accessory electrodes 29, a positive (+) voltage isapplied to the display electrodes 3 a and the accessory electrodes 20,and a negative (−) voltage to the display electrodes 3 b, so that thedisplay area 30 as a whole is charged positively, as shown in FIGS. 24to 26. Further, spacers 8 are charged negatively and then sprayed.

In this way, it is possible to dispose spacers 8 only in each spacebetween the paired display electrodes 3 a in a manner such that spacers8 can be disposed uniformly in spaces between respective paired displayelectrodes 3 a throughout the display area 30 including those spacesbetween respective paired display electrodes 3 a in the vicinity of theedge portions of the display area 30.

Thus, as shown in FIG. 24 and FIG. 25, as the sprayed and fallingspacers 8 approach the display electrodes 3 a and 3 b, a repulsive forceand an attractive force act on the spacers 8, where both the forces areexerted by the electric fields generated above the display electrodes 3a and 3 b and the accessory electrodes 29, and each spacer goes awayfrom the display electrode 3 b exerting a repulsive force on it, andmoves toward the display electrode 3 a and accessory electrode 29generating an attractive force. The spacer 8 that has moved to thedisplay electrode 3 a is attracted by equal attractive forcesrespectively exerted by the two neighboring display electrodes 3 a andfalls between the display electrodes 3 a.

Since the display area 30 as a whole is positively charged, anattractive force acts on spacers 8 in the vicinity of each edge portionof the display area 30 and tends to move them into the display area 30from outside the display area 30, as shown in FIG. 26. This movement ofspacers 8 from the outside of the display area 30 into the display area30, however, can be prevented, and the density of spacers 8 disposed inrespective spaces between paired display electrodes 3 a can bemaintained at a predetermined level since a voltage capable ofgenerating an attractive force is applied to the accessory electrodes29.

FIG. 27 is a schematic view showing an electrode pattern to be used inthe practice of the second aspect of the invention.

FIG. 28 is a schematic view showing an electrode pattern for oneinsulating substrate in the production of two liquid crystal displaydevices from a pair of insulating substrates in an embodiment of thesecond aspect of the invention. As shown in FIG. 27 and FIG. 28, theaccessory electrodes 29 are disposed outside the display area 30 so asto surround the display area 30.

The accessory electrodes 29 are each connected with a conductor wire 18for voltage application to the accessory electrodes 29 for electricfield formation. A voltage may also be applied directly to the accessoryelectrodes 29 by means of probe pins or the like without providing suchconductor wire 18. The display electrodes 3 a occur in pairs of twoneighboring display electrodes. The display electrodes 3 b occur betweena pair of display electrodes 3 a and another pair of display electrodes3 a. In FIG. 27, one display electrode 3 b occurs between two pairs ofdisplay electrodes 3 a.

By using such an insulating substrate electrode pattern as shown in FIG.28 and applying, according to such an electrode pattern as shown in FIG.27, voltages differing in voltage value are applied to the displayelectrodes 3 a and 3 b and the accessory electrodes 29, a positive (+)voltage is applied to the display electrodes 3 a, and a negative (−)voltage is applied to the display electrodes 3 b and the accessoryelectrodes 29, so that the display area 30 as a whole is chargednegatively, as shown in FIGS. 29 to 31. Further, spacers 8 are chargednegatively and then sprayed.

In this way, it is possible to dispose spacers 8 only in each spacebetween the paired display electrodes 3 a in a manner such that spacers8 can be disposed uniformly in spaces between respective paired displayelectrodes 3 a throughout the display area 30 including those spacesbetween respective paired display electrodes 3 a in the vicinity of theedge portions of the display area 30.

Thus, as shown in FIG. 29 and FIG. 30, as the sprayed and fallingspacers 8 approach the display electrodes 3 a and 3 b, a repulsive forceand an attractive force act on the spacers 8, where both the forces areexerted by the electric fields generated above the display electrodes 3a and 3 b and the accessory electrodes 29, and each spacer goes awayfrom the display electrode 3 b or accessory electrode 29 each exerting arepulsive force on it and moves toward the display electrode 3 agenerating an attractive force. The spacer 8 that has moved to thedisplay electrode 3 a is attracted by equal attractive forcesrespectively exerted by the two neighboring display electrodes 3 a andfalls between the display electrodes 3 a.

Since the display area 30 as a whole is in a state equivalent to thestate of being negatively charged, a repulsive force acts on spacers 8in the vicinity of each edge portion of the display area 30, and tendsto move them outside the display area 30, as shown in FIG. 31. Thismovement of spacers 8 to the outside of the display area 30 can beprevented, however, since a voltage capable of generating a repulsiveforce is applied to the accessory electrodes 29.

FIG. 32 is a schematic view showing an electrode pattern to be used inthe practice of the second aspect of the invention. As shown in FIG. 32,auxiliary electrodes 20 a and 20 b are formed on an insulating substrate1 for voltage application respectively to the display electrodes 3 a and3 b and stripe-shaped display electrodes 3 a and 3 b. Further,additional display electrodes 3 a and 3 b are formed outside the displayarea 30 so that the display electrodes 3 a formed outside the displayarea 30 may serve as accessory electrodes 29 a and the displayelectrodes 3 b formed outside the display area 30 may be served asaccessory electrodes 29 b.

Conductor wires 18 a and 18 b are connected with the auxiliaryelectrodes 20 a and 20 b for electric field formation by applyingvoltages to the auxiliary electrodes 20 a and 20 b. Voltages may beapplied directly to the auxiliary electrodes 20 a and 20 b by means ofprobe pins or the like without providing the conductor wires 18 a and 18b, or voltages may be applied directly to the display electrodes 3 a and3 b and to the accessory electrodes 29 a and 29 b by means of probe pinsor the like without providing the auxiliary electrodes 20 a and 20 b.

The display electrodes 3 a occur in pairs of two neighboring displayelectrodes. The display electrodes 3 b occur between a pair of displayelectrodes 3 a and another pair 30 of display electrodes 3 a. In FIG.32, one display electrode 3 b occurs.

The accessory electrodes 29 are disposed only in those areas outside thedisplay area 30 as seen in the vertical direction of FIG. 32. This isbecause the auxiliary electrodes 20 a and 20 b are formed in those areasoutside the display area 30 as seen in the horizontal direction of FIG.32, and the auxiliary electrodes 20 a and 20 b produce the same effectas the accessory electrodes 29.

By applying voltages differing in voltage value to the auxiliaryelectrodes 20 a and 20 b according to such an electrode pattern as shownin FIG. 32, negative (−) voltages are applied to the display electrodes3 a and 3 b and the accessory electrodes 29 a and 29 b in a manner suchthat a relatively higher voltage is applied to the display electrodes 3a and accessory electrodes 29 a as compared with the display electrodes3 b and accessory electrodes 29 b, as shown in FIGS. 33 to 35. Further,spacers 8 are charged negatively and then sprayed.

In this way, it is possible to dispose spacers 8 only in each spacebetween the paired display electrodes 3 a in a manner such that spacers8 can be disposed uniformly in spaces between respective paired displayelectrodes 3 a throughout the display area 30 including those spacesbetween respective paired display electrodes 3 a in the vicinity of theedge portions of the display area 30.

Thus, as shown in FIG. 33 and FIG. 34, as the sprayed and fallingspacers 8 approach the display electrodes 3 a and 3 b, a repulsive forceacts on the spacers 8, where said force is exerted by the electric fieldgenerated above the display electrodes 3 a and 3 b and accessoryelectrodes 29, and each spacer goes away from the display electrode 3 bexerting a strong repulsive force on it, and moves toward the displayelectrode 3 a generating a weak repulsive force. The spacer 8 that hasmoved to the display electrode 3 a is pushed by equal repulsive forcesrespectively exerted by the two neighboring display electrodes 3 a, andfalls between the display electrodes 3 a.

Since the electrode pattern as a whole is negatively charged, therepulsive force acting on spacers 8 in the vicinity of each edge portionof the electrode pattern tends to move them outside the display area 30,as shown in FIG. 35. Since, however, it is accessory electrodes 29 a and29 b that are located in the vicinity of each edge portion of theelectrode pattern as seen in the vertical direction of FIG. 35, it doesnot matter if no spacer 8 is disposed in the vicinity of the edgeportions of the electrode pattern. In other words, the display area 30is located in the middle of the electrode pattern, so that spacers 8 canbe disposed at a predetermined density in the display area 30.

By using such an insulating substrate electrode pattern as shown in FIG.17 and applying, according to such an electrode pattern as shown in FIG.11, voltages differing in voltage value to the auxiliary electrodes 20 aand 20 b and the accessory electrodes 29, a positive (+) voltage isapplied to the display electrodes 3 a and 3 b and accessory electrodes29 in a manner such that a relatively higher voltage is applied to thedisplay electrodes 3 b and accessory electrodes 29 as compared with thedisplay electrodes 3 a, as shown in FIGS. 36 to 38. Further, spacers 8are charged positively and then sprayed.

In this way, it is possible to dispose spacers 8 only in each spacebetween the paired display electrodes 3 a in a manner such that spacers8 can be disposed uniformly in spaces between respective paired displayelectrodes 3 a throughout the display area 30 including those spacesbetween respective paired display electrodes 3 a in the vicinity of theedge portions of the display area 30.

Thus, as shown in FIG. 36 and FIG. 37, as the sprayed and fallingspacers 8 approach the display electrodes 3 a and 3 b, a repulsive forceact on the spacers 8, where said force is exerted by the electric fieldgenerated above the display electrodes 3 a and 3 b and accessoryelectrodes 29, and each spacer goes away from the display electrode 3 band accessory electrode 29 both exerting a strong repulsive force on itand moves toward the display electrode 3 a generating a weak repulsiveforce. The spacer 8 that has moved to the display electrode 3 a ispushed by equal repulsive forces respectively exerted by the twoneighboring display electrodes 3 a and falls between the displayelectrodes 3 a.

Since the display area 30 as a whole is positively charged, a repulsiveforce acts on spacers 8 in the vicinity of each edge portion of thedisplay area 30, and tends to move them outside the display area 30, asshown in FIG. 38. This movement of spacers 8 to the outside of thedisplay area 30, however, can be prevented since a voltage capable ofgenerating a strong repulsive force is applied to the accessoryelectrodes 29.

In the above embodiment, spacers 8 fall into each space between twoneighboring display electrodes 3 a while they are pushed by equalrepulsive forces respectively exerted by the display electrodes 3 a, sothat the spacers 8 can be disposed concentratedly in the middle of eachspace between display electrodes 3 a and thus the probability thatspacers 8 may be disposed on edge areas of the display electrodes 3 acan be minimized.

While several embodiments of the second aspect of the invention havebeen described hereinabove, the second aspect of the invention is notlimited to the embodiments described but the same effects as mentionedabove can be produced, with negatively charged spacers 8, based on therelation between relatively higher and lower voltages according to thepresent invention, as shown in FIG. 39.

FIG. 39 is a schematic representation of the relation between therelative level of the voltage applied to the display electrodes and themagnitude of the repulsive or attractive force exerted on spacers 8 bythe voltage in the case where spacers 8 are negatively charged.

The relatively higher or lower voltage and the voltage polarity areshown in terms of + or −, with the earth voltage of 0 V at which norepulsive or attractive force acts on spacers 8 being taken as thereference voltage.

Thus, according to FIG. 39, +300 V, for instance, is a voltagerelatively lower than +500 V and −300 V is a voltage relatively higherthan −500 V.

Between a display electrode and a spacer 8 separated by a certaindistance from each other, the electric field formed above the displayelectrode exerts a repulsive force or attractive force upon the spacer 8depending on the polarity of the voltage applied to the displayelectrode. According to FIG. 39, where the spacer 8 has a negativepolarity, a repulsive force is produced when the voltage is of negativepolarity (−) while an attractive force is generated when the voltage isof positive polarity. The magnitude of this repulsive becomes greater asthe voltage shifts to the more negative (−) polarity side while that ofthe attractive force becomes greater as the voltage shifts to the morepositive (+) polarity side.

Thus, +500 V, for instance, produces a greater attractive force than+300 V while −500 V produces a greater repulsive force than −300 V.

In cases where spacers 8 are charged positively, an attractive force isexerted in lieu of a repulsive force and vice versa. Thus, a voltage ofnegative (−) polarity gives rise to an attractive force while a voltageof positive (+) polarity gives rise to a repulsive force. And, thisattractive force becomes greater as the voltage shifts to the morenegative (−) polarity side, while the repulsive force increases as thevoltage shifts to the more positive (+) side.

Thus, +500 V, for instance, produces a greater repulsive force than +300V while −500 V produces a greater attractive force than −300 V.

According to the definition of the relative level of voltage as madeherein, a voltage is lower when it is on the more negative (−) polarityside, and a voltage is higher when it is on the more positive (+)polarity side, as shown in FIG. 39, irrespective of the magnitude offorce acting on spacers 8.

Thus, +500 V is defined as a higher voltage than +300 V, and −500 V isdefined as a lower voltage than −300 V.

This definition also applies to cases where spacers 8 are chargedpositively. Thus, +500 V is defined as a higher voltage than +300 V, and−500 V is defined as a lower voltage than −300 V.

Now, referring to FIG. 40 and FIG. 41, troubles encountered when noaccessory electrodes are provided are explained.

FIG. 40 is a schematic view showing the state of the display area 30being as a whole charged negatively when no accessory electrodes 29 areprovided. As shown in FIG. 40, the display area 30 as a whole is chargednegatively, so that when spacers are negatively charged and sprayed, arepulsive force acts on the spacers 8.

In the middle of the display area 30, spacers 8 are subjected torepulsive forces uniformly from around and therefore the spacers 8undergo only the influence of a local electric field and are disposedbetween the paired display electrodes 3 a. In the vicinity of each edgeportion of the display area 30, however, they undergo a repulsive forcedue to the electric field above the display area 30 as a whole andmigrate to the outside of the display area 30 where no electric field isformed. Thus, a trouble arises that spacers 8 are hardly disposed in apredetermined amount in those display electrode (3 a) gaps in thevicinity of the edge portions of the display area 30.

On the other hand, FIG. 41 is a schematic view showing the case in whichthe display area 30 as a whole is charged positively but no accessoryelectrodes are provided. As shown in FIG. 41, an attractive force actson spacers 8, when they are charged negatively and sprayed, since thedisplay area 30 as a whole is positively charged.

In the middle of the display area 30, spacers 8 are subjected toattractive forces uniformly from around and therefore the spacers 8undergo only the influence of a local electric field and are disposedbetween the paired display electrodes 3 a. In the vicinity of each edgeportion of the display area 30, however, they undergo an attractiveforce due to the electric field above the display area 30 as a whole andmigrate from the outside of the display area 30, where no electric fieldis formed to the inside of the display area 30. Thus, a trouble arisesthat spacers 8 are more abundantly than a predetermined amount in thosedisplay electrode (3 a) gaps in the vicinity of the edge portions of thedisplay area 30.

In the embodiments mentioned above, the electric field is controlled byproviding accessory electrodes 29 on the insulating substrate havingdisplay electrodes formed thereon. There is another method available bywhich it is also possible to produce the same effects, said methodcomprising providing accessory electrodes 29 on a stage for fixingthereon the insulating substrate with display electrodes formed thereonor on the wall of the spacer sprayer, and applying a voltage thereto.

According to the second aspect of the invention, it is also possible toadjust the density of spacers disposed in the vicinity of the edgeportions of the display area 30 by adjusting the voltage applied to theaccessory electrodes 29, and it is further possible to finely controlthe liquid crystal layer thickness of the liquid crystal display deviceby controlling the space disposition density.

Furthermore, while, in the above embodiments, simple matrix type liquidcrystal display devices are employed, the second aspect of the inventionis not limited to simple matrix type liquid crystal display devices, butcan of course be applied to the production of ferroelectric liquidcrystal display devices, TFT type liquid crystal display devices andlike liquid crystal display devices as well.

The method for producing a liquid crystal display device according tothe third aspect of the invention comprises

spraying spacers onto at least one of a first substrate comprising atleast pattern-forming transparent electrodes and a dummy electrode and asecond substrate to be disposed opposedly above the first substrate

and filling a liquid crystal into the space between both the substrates,

wherein, in spraying positively or negatively charged spacers onto thesubstrate, two or more voltages differing in voltage value are appliedto respective transparent electrodes and a voltage is applied to thedummy electrode as well,

the predetermined transparent electrode gaps in which spacers are to beselectively disposed are provided between respective two neighboringtransparent electrodes,

the number of transparent electrodes is even,

and the two or more voltages differing in value are applied in a mannersuch that when the spacer charge polarity is positive (+), the lowest ofthe two or more voltages differing in value is applied to the respectivetwo neighboring transparent electrodes between which spacers are to bedisposed in the middle, and when the spacer charge polarity is negative(−), the highest of the two or more voltages differing in value isapplied to the respective two neighboring transparent electrodes betweenwhich spacers are to be disposed in the middle.

The above transparent electrodes, dummy electrodes, substrate, spacersand spacer charging method are the same as described referring to thefirst aspect of the invention. The method for producing a liquid crystaldisplay device according to the third aspect of the invention can beapplied to the production of TFT type liquid crystal display devices, asexplained hereinabove referring to the second aspect of the invention.

The predetermined transparent electrode gaps in which spacers are to beselectively disposed are those transparent electrode gaps to thetransparent electrodes of which the lowest of the two or more voltagesdiffering in value applied to the transparent electrodes is applied whenspacers are charged positively (+), and the predetermined transparentelectrode gaps are those transparent electrode gaps to the transparentelectrodes of which the highest of the two or more voltages differing invalue applied to the transparent electrodes is applied when spacers arecharged negatively (−).

When, for example, strong repulsive forces and weak repulsive forces arearranged regularly as shown in FIG. 14, each trough or crest of asynthetic repulsive force occurs in the middle of a region oftransparent electrodes exerting a weak repulsive force or of a region oftransparent electrodes exerting a strong repulsive force (such a regionas shown in FIG. 9).

Therefore, in the case of FIG. 14, spacers are disposed in the middle ofweak repulsive forces and therefore it is only necessary that the spacebetween transparent electrodes be there. For achieving this, the numberof transparent electrodes exerting a weak repulsive force should beeven; in that case, the centerline of the relevant region corresponds tothe space between the relevant transparent electrodes.

Further, when repulsive forces and attractive forces are arrangedregularly as shown in FIG. 22, each trough or crest of the synthesis ofa repulsive force and an attractive force occurs in the middle of aregion of transparent electrodes exerting a repulsive force or of aregion of transparent electrodes exerting an attractive force (such aregion as shown in FIG. 9).

Therefore, in the case of FIG. 22, spacers are disposed in the middle ofattractive forces and it is only necessary that the centerline betweentransparent electrodes be there. For achieving this, the number oftransparent electrodes exerting an attractive force should be even; inthat case, the centerline of the relevant region corresponds to thespace between the relevant transparent electrodes.

If, however, the number of transparent electrodes exerting a weakrepulsive force is odd in the case of FIG. 14 or the number oftransparent electrodes exerting an attractive force is odd in the caseof FIG. 22, each location where spacers are disposed occurs on thecenterline of a transparent electrode.

In cases where the spacer charge polarity is negative (−), the voltageapplication to the transparent electrodes is carried out by providing acommon conductor line (A) which is connected with one of the two ends ofeach transparent electrode, to which the highest voltage is to beapplied, and applying the highest voltage by means of the conductor line(A), while providing a common conductor line (B) which is connected withone end, on the opposite side of the one end mentioned above, of the twoends of each transparent electrode, to which a lower voltage is to beapplied, and applying the lower voltage by means of the conductor line(B) and, in cases where the spacer charge polarity is positive (+), thevoltage application to the transparent electrodes is carried out byproviding a common conductor line (A) which is connected with one of thetwo ends of each transparent electrode to which the lowest voltage is tobe applied and applying the lowest voltage by means of the conductorline (A) while providing a common conductor line (B) which is connectedwith one end, on the opposite side of the one end mentioned above, ofthe two ends of each transparent electrode to which a higher voltage isto be applied and applying the higher voltage by means of the conductorline (B).

For example, by using such comb-shaped electrodes having a 2:1 structureas shown in FIG. 42 and applying the highest voltage to the conductorline (A), and a voltage lower than the above voltage to the conductorline (B) when the spacer charge polarity is negative (−), it is possibleto dispose spacers in spaces or gaps (a). After spacer disposition, theconductor lines (A) and (B) are cut off along the dotted lines in thefigure, to give stripe-shaped transparent electrodes.

As mentioned above, the third aspect of the present invention makes itpossible to dispose spacers in interelectrode spaces where notransparent electrode exists, namely at sites of within the blackmatrix, by applying, in spacer spraying, two or more voltages differingin value to the pattern-forming transparent electrodes.

If, in spacer spraying, no voltage is applied to the dummy electrode andtwo or more voltages differing in value are simply applied to thetransparent electrodes, respectively, the phenomenon of the number ofspacers increasing or decreasing in the vicinity of the periphery of thedisplay area is observed, as detailedly described hereinbefore referringto the first and second aspects of the present invention, and the spacerdistortion varies, the cell thickness varies and the display on theproduct liquid crystal display device becomes uneven, as explainedhereinabove referring to the first and second aspects of the presentinvention.

For preventing these phenomena, a voltage is applied to the dummyelectrode as well according the third aspect of the present invention,whereby the irregularities in the number of spacers disposed as observedbetween the inside of the display area and the vicinity of the peripherythereof can be prevented from occurring, hence the irregularities incell thickness caused by the above irregularities can be dissolved. As aresult, liquid crystal display devices uniform in displaycharacteristics can be obtained.

The dummy electrodes are the same as those mentioned hereinabovereferring to the first aspect of the present invention.

In the following, mention is made of the voltage application to thedummy electrodes.

The voltage to be applied to the dummy electrode is preferably withinthe range between the highest and the lowest of the two or more voltagesdiffering in value which are applied to the transparent electrodes.Thus, the number of spaces disposed is caused to decrease or increase inthe dummy electrode sections by extending the electric field formedabove the transparent electrodes and comprising relatively high voltage(+ (positive)) and relatively low voltage (− (negative)) regions toabove the dummy electrodes, as shown in FIG. 43. As a result, spacersare disposed uniformly in the display area.

The voltage application to the dummy electrodes is preferably carriedout by connecting one of the conductor lines (A) and (B) with the dummyelectrodes.

For example, by connecting the conductor line (B) with the dummyelectrodes, as shown in FIG. 44, it becomes possible to apply the sameelectric potential to the conductor line (B) and the dummy electrodes.While, in the case shown in FIG. 44, the conductor line (B) is formed asan electrode integrated with the dummy electrodes, the conductor line(A) may be formed as an electrode integrated with the dummy electrodesor, further, the conductor line (A) or (B) and the dummy electrodesseparately and independently provided on the substrate may be connectedwith each other by wiring.

The voltage application to the dummy electrodes can also be carried outby connecting all dummy electrodes formed on the substrate with oneanother.

For example, by wiring to thereby connect all dummy electrodes formed onthe substrate with one another, as shown in FIG. 45, it becomes possibleto apply the same electric potential to all the dummy electrodes.

The method for producing a liquid crystal display device according tothe fourth aspect of the present invention comprises

spraying spacers onto at least one of a first substrate comprising atleast pattern-forming transparent electrodes and a dummy electrode and asecond substrate to be disposed opposedly above the first substrate

and filling a liquid crystal into the space between both the substrates,

wherein, in spraying positively or negatively charged spacers onto thesubstrate, the substrate is disposed in close contact with an earthedconductive stage,

a conductor is provided in a state electrically isolated from theconductive stage,

said conductor being a conductive frame having an opening and saidconductive frame being disposed on the periphery of the substrate withor without partial overlapping with the substrate periphery,

and wherein a voltage is applied to the transparent electrode and theconductive frame.

The above pattern-forming transparent electrodes, substrate, spacers andspacer charging method are the same as explained referring to the firstaspect of the invention. As explained referring to the second aspect ofthe invention, the method for producing a liquid crystal display deviceaccording to the fourth aspect of the invention can be applied to theproduction of TFT type liquid crystal display devices.

In accordance with the fourth aspect of the invention, spacers can bedisposed in electrode gaps, without any trouble in spacer disposition,even when an electric field exerting a repulsive force is formed abovethe pattern-forming transparent electrodes by applying a voltage of thesame polarity as the spacer charge polarity to the pattern-formingtransparent electrodes in a state such that the substrate with the blackmatrix formed thereon is in close contact with the conductive stage.

If, here, a voltage is merely applied to the transparent electrodes, thephenomenon of the number of spacers increasing or decreasing in thevicinity of the periphery of the display area is observed, as explainedin detail referring to the first and second aspects of the invention,causing variations in spacer distortion and in cell thickness in theproduction of liquid crystal display devices and causing uneven displayof the liquid crystal display devices.

It is conceivable that the distribution of spacers in the display areaand the region outside the display area might be controlled by using adummy electrode generally used for preventing the build-up of staticelectricity on the substrate and applying a voltage of the same polarityas the transparent electrode polarity to the dummy electrodes to therebyrender the repulsive force resulting from the electric field above thesubstrate uniform all over the substrate. For realizing this method,however, it is necessary that the dummy electrodes be present also inthe outside of the display area to thereby secure a sufficiently widerange for spacer spraying. This is unfavorable from the space viewpoint.

For preventing these phenomena, the substrate is disposed in closecontact with an earthed conductive stage, and a conductor is provided ina state electrically insulated from the conductive stage in sprayingpositively or negatively charged spacers according to the fourth aspectof the invention. The conductor is a conductive frame having an openingand is disposed on the periphery of the substrate with or withoutpartial overlapping with the substrate periphery, and a voltage isapplied to the transparent electrode and the conductive frame as well tothereby form an electric field outside the substrate as well which isalmost the same as that within the substrate. The range of the repulsiveforce above the substrate is thereby extended and the risk of the numberof spacers increasing or decreasing is absorbed in the region outsidethe substrate, so that the display area can become uniform with respectto the number of spacers.

The earthed conductive stage preferably has a volume resistance value ofnot more than 1×10¹⁰ Ωcm. When the volume resistance value is in excessof 1×10¹⁰ Ωcm, the whole substrate becomes close in electric potentialto the transparent electrodes, with the result that the accuracy ofspacer disposition becomes poor.

Since if there is an electrically floating electrode, spacers aresprayed concentratedly thereon, the method of applying a voltage of thesame polarity as the spacer charge polarity to the transparentelectrodes formed on the substrate is preferably carried out by applyingthe voltage to all transparent electrodes to thereby eliminate theoccurrence of such electrically floating electrode.

The material of the above conductor is not particularly restricted butmay be, for example, a metal such as aluminum, iron, copper or stainlesssteel; or a resin rendered conductive by coating with a metal or thelike. The conductor may be made of a laminate produced by placing a thinmetal foil or sheet, such as aluminum foil or copper foil, on a resinlayer.

In the case of multipanel substrates for producing a plurality of liquidcrystal panels per glass substrate, the shape of the above conductor maybe such that it has openings corresponding to the respective displayareas.

The method of insulating the above conductive stage from the conductoris not particularly restricted but, for example, an insulator, such as aresin, may be insulated therebetween, or a space is providedtherebetween for attaining insulation by air.

The method of voltage application to the substrate is not particularlyrestricted but, for example, may be the method comprising providing adummy electrode around the linear transparent electrodes on thesubstrate, as shown in FIG. 2, connecting the dummy electrode with thelinear transparent electrodes and carrying out voltage application tothe dummy electrode via the conductive frame in a state electricallyinsulated from the conductive stage on which the substrate is disposed.The method of voltage application from the conductive frame to the dummyelectrode is not particularly restricted but may be, for example, themethod comprising forming a needle-like body or bodies extending fromthe conductive frame.

The voltage to be applied to the transparent electrodes on the substrateand to the conductive frame preferably has a value of several hundred toseveral thousand volts. When the voltage applied to too low, it becomesdifficult to control the route of falling of spacers. If the voltageapplied is too high, short-circuiting may occur between the transparentelectrodes and the black matrix when the latter is a conductive one.

The conductor mentioned above may be made from a flat conductor or froma net-, bar- or wire-like conductor. When it is made from a flat sheetconductor, the sheet maybe processed by perforation or the like toproduce a structure for improving the flow of air.

Now, referring to FIGS. 46 to 51, specific embodiments of the method forproducing a liquid crystal display device according to the fourth aspectof the invention are described.

FIG. 46 shows an embodiment of the fourth aspect of the invention fordual-panel substrates. A conductive frame is formed on the conductivestage while placing a resin or like insulator identical in thickness tothe first substrate. The conductive frame is disposed in a stateoverlapping with the periphery of the substrate. In this way, theconductive frame overlaps with the periphery of the substrate and can bedisposed without leaving any gap.

In an embodiment of the fourth aspect of the invention, which is shownin FIG. 47, a conductive frame, which is provided with an openingidentical in shape and size with the substrate, is placed on theconductive stage with an insulator sandwiched therebetween.

When a voltage of the same polarity as the transparent electrodepolarity is applied to the conductive frame, the range of the repulsiveelectric field is enlarged and the risk of the number of spacersincreasing or decreasing is absorbed in the conductor frame portion,hence the distribution of spacers within the display area becomesuniform.

The mechanism of disposition of the above conductive stage andconductive frame may be such that the conductive frame preparedseparately be put on the stage from above or they be hinged together forclosing and opening.

FIG. 48 shows the state of sprayed spacers in the method for producing aliquid crystal display device according to the fourth aspect of theinvention, wherein repulsive forces are utilized.

In the case of FIG. 47, for instance, the range of the repulsiveforce-exerting electric field can be enlarged by voltage application toall the stripe-shaped transparent electrodes, dummy electrode(s) andconductive frame and, therefore, the uniformity of the display area canbe improved. The electrode structure to be employed in this case is asshown in FIG. 2 or FIG. 3.

When the dummy electrode is connected with the transparent electrodes,it becomes possible to carry out voltage application to the dummyelectrode via the conductive frame electrically insulated from theconductive stage on which the substrate is disposed.

The voltage application to the dummy electrode from the conductive framecan be carried out, for example, by forming a needle-like body on theflat sheet surface facing the substrate on the conductive frame, on theconductive frame-forming flat sheet or on a side of the conductiveframe, as shown in FIG. 49 or FIG. 50.

In some instances, depending on the distance between the conductiveframe and display area, the uniformity may not be secured unless avoltage differing from the voltage applied to the transparent electrodesis applied to the conductive frame.

When, for example, repulsive forces are utilized for spacer dispositionand the display area is away from the conductive frame, as shown in FIG.51, spacers may escape into the space therebetween. In such a case, itis necessary to apply, to the conductive frame, a voltage producing arepulsive force stronger than that within the display area to therebyrepel spacers oppositely toward the periphery of the display areautilizing the repulsive force.

In accordance with the method according to the fourth aspect of theinvention which comprises effecting spacer charging and applying avoltage to the transparent electrodes to thereby dispose spacers ininterelectrode gaps, the falling of spacers is controlled by disposing aconductive frame (conducting frame) on the periphery of the substrateand applying a voltage thereto, so that spacers can be disposed all overthe substrate, to give a uniform cell gap and high quality displaycharacteristics without display unevenness.

After completion of spacer spraying, the above conductive frame isremoved and, thereafter, a liquid crystal display device can be producedby disposing a second substrate opposedly to the first substrate in theconventional manner and filling a liquid crystal into the spacetherebetween.

The method for producing a liquid crystal display device according tothe fifth aspect of the present invention comprises

spraying spacers onto at least one of a first substrate comprising atleast pattern-forming transparent electrodes and an alignment layer andhaving a display area and a second substrate to be disposed opposedlyabove the first substrate

and filling a liquid crystal into the space between both the substrates

wherein, in spraying positively or negatively charged spacers onto thesubstrate, the substrate is disposed in close contact with an earthedconductive stage,

a voltage having the same polarity as the spacer charge polarity isapplied to the transparent electrodes on the substrate,

a conductor is provided, outside the display area, in a stateelectrically insulated from the conductive stage,

and a voltage having the same polarity as the polarity of the voltageapplied to the transparent electrodes is applied to the conductor tothereby form an electric field outside the substrate as well which isalmost the same as the electric field within the substrate.

The above transparent electrodes, substrate, spacers and spacer chargingmethod are the same as those described hereinbefore referring to thefirst aspect of the invention. The method of liquid crystal displaydevice according to the fifth aspect of the invention can be applied tothe production of TFT type liquid crystal display devices, as explainedhereinabove referring to the second aspect of the invention.

When, for example, the substrate comprising at least pattern-formingtransparent electrodes and an alignment layer and having at least onedisplay area is not earthed or is disposed in close contact with aconductive stage, which is not earthed, as shown in FIG. 52, and avoltage of the same polarity as the charge polarity of charged spacersis applied to the pattern-forming transparent electrodes on thesubstrate in spraying charged spacers, the resulting electric field isnearly uniform (as shown in FIG. 52 as an equipotential surface at acertain electric potential), hence no selective spacer disposition iseffected.

On the other hand, when the substrate is disposed in close contact withan earthed conductive stage, as shown in FIG. 53, and a voltage of thesame polarity as the charge polarity of charged spacers is applied tothe pattern-forming transparent electrodes on the substrate, theelectric potential lowers above each transparent electrode gap (as shownin FIG. 53 as a certain equipotential surface at a certain electricpotential), hence spacers can be disposed in the transparent electrodegap under the action of a repulsive force.

However, in cases where an electric field is formed by the voltageapplied to the pattern-forming transparent electrodes and a repulsiveforce acts on spacers, the phenomenon of the number of spacersdecreasing in the vicinity of the periphery of the display area isobserved and, as explained referring to the first and second aspects ofthe invention, the spacer distortion becomes varied and the cellthickness varies in the method for producing a liquid crystal displaydevice and the display on the product liquid crystal display devicebecomes uneven.

The cause of such an increase or decrease in number of spacers in thevicinity of the periphery of the display area is as follows. Whenspacers are intended to be disposed in transparent electrode gaps byapplying a voltage of the same polarity as the spacer charge polarity tothe pattern-forming transparent electrodes, a force (repulsive force)acts on falling spacers to repel them from within the display area tothe outside of the display area, as shown in FIG. 1, FIG. 52 and FIG.53. In particular, in the vicinity of the periphery of the display area,spacers to be disposed in the peripheral portions of the display areaescape to the outside since there is no repulsive force above thesubstrate portions outside the display area and, when the region outsidethe display area is large, spacers are disposed concentratedly in theregion outside the display area.

For preventing these phenomena, the fifth aspect of the inventioncomprises disposing, in spraying positively or negatively chargedspacers onto the substrate, the substrate in close contact with anearthed conductive stage, applying a voltage of the same polarity as thespacer charge polarity to the transparent electrode on the substrate,providing, outside the display area, a conductor in a state electricallyinsulated from the conductive stage, and applying a voltage of the samepolarity as that of the voltage applied to the transparent electrodes tothereby form an electric field on the outside of the substrate almostsame as the electric field within the substrate. The result is that therange of the effective repulsive force above the substrate is enlarged,the increase or decrease in number of spacers is absorbed in the regionoutside the substrate, and the number of spacers becomes uniform withinthe display area.

The earthed conductive stage, the method of applying a voltage of thesame polarity as the spacer charge polarity to the transparentelectrodes formed on the substrate, the material of the conductor, theshape and size of the conductor, the method of insulating the conductorfrom the conductive stage, the method of voltage application to thesubstrate, the voltage values to be applied to the transparentelectrodes on the substrate and to conductive frame, and the method offorming the conductive frame are the same as those mentioned hereinabovereferring to the fourth aspect of the invention.

The voltage to be applied to the conductive frame is preferablyapproximately the same as or higher than the voltage applied to thetransparent electrodes. If the voltage applied to the conductive frameis lower than that applied to the transparent electrodes, the decreasein number of spacers on the periphery of the substrate cannot beprevented.

In cases where different voltages are applied to the conductive frameand the transparent electrodes, terminals from different voltage supplyapparatus are connected with them, respectively.

Referring to FIG. 55 to 60, specific examples of the method forproducing a liquid crystal display device according to the fifth aspectof the invention are now described.

FIG. 55 is a schematic view illustrating the relation between thesubstrate and conductive frame, in the method for producing a liquidcrystal display device according to the fifth aspect of the invention.In accordance with the fifth aspect of the invention, the conductor is aconductive frame having greater outer dimensions as compared with thesubstrate, as shown in FIG. 55, and has an opening greater in size thanthe display area but smaller in size than the substrate. The conductiveframe is disposed with or without overlapping with the peripheralportions of the substrate, and a voltage of the same polarity as that ofthe voltage applied to the transparent electrodes is preferably appliedto the conductive frame.

The above conductive stage and conductive frame may be formed eitherindividually or partitionedly on one and the same insulating flat sheet,as shown in FIG. 56.

The position where the above conductive frame is to be formed is notparticularly restricted but may be, for example, above the substrateplane, on the same level as the substrate or conductive stage, or belowthe conductive stage.

In cases where the opening of the conductive frame is smaller in sizethan the substrate and the conductive frame is placed on the substrate,as shown in FIG. 55(1), or in cases where the opening of the conductiveframe is identical with the substrate and the upper surface of theconductive frame is on the same level as the substrate surface, as shownin FIG. 55 (2), for instance, no particular problem arises if theconductive frame is greater than the substrate and conductive stage; itis only necessary that the insulation of the conductive stage from theconductive frame be secured.

In cases where the opening of the conductive frame is smaller in sizethan the substrate and the conductive frame is placed on the substrate,the conductive frame itself serves as a mask and, therefore, spacerswill not be disposed concentratedly in the peripheral region of thesubstrate where there is no transparent electrode.

In cases where the opening of the conductive frame is identical in sizewith the substrate and the upper surface of the conductive frame is onthe same level as the substrate surface, however, no repulsive forceacts above the peripheral region of the substrate where no transparentelectrode exists, so that spacers may be disposed on the peripheralregion of the substrate in a locally concentrated manner. When theconductive frame is smaller than the conductive stage, spacers may bedisposed in a locally concentrated manner on the protruding portions ofthe conductive stage.

The above local concentration of spacers means the escape of spacersfrom the periphery of the display area to the sites of concentration.This causes a decrease in number of spacers on the periphery of thedisplay area and, as a result, the cell thickness may possibly becomeirregular in the product liquid crystal display device.

In cases where the conductive frame is located on the substrate, thesubstrate can come into full contact with the conductive stage. The sizeof the conductive stage is not particularly restricted but, for example,may be greater or smaller than the substrate size.

As regards the spacer disposition, the electric potential above eachtransparent electrode gap is lowered and an electric field suited forthe disposition is formed by disposing the substrate into close contactwith the conductive stage. Therefore, in cases where the conductiveframe is disposed on the lower (reverse) side of the substrate, theconductive frame is in contact with the under (reverse) surface of thesubstrate, so that the electric potential of the substrate in thecontact region rises and the spacer disposition quality may become pooras the case may be.

It is preferred that the above conductive stage be not greater in sizethan the substrate but large enough to cover the region outside theparting lines and the conductive frame upper surface be on almost thesame level as the conductive stage surface, as shown in FIG. 55(3), orthe conductive frame be disposed at a position lower than the conductivestage, as shown in FIG. 55(4).

The parting lines are those lines based on which the first and secondsubstrates, after panel alignment, are cut.

In cases where the dummy electrodes are provided in the region outsidethe display area on the substrate, the region outside the parting linesis the dummy electrode region, as shown in FIG. 59.

When the conductive frame upper surface is on the almost same level asthe conductive stage surface, the substrate comes into contact with theconductive frame, as shown in FIG. 55(3). When the conductive frame isdisposed at a position lower than the conductive stage, a state arisessuch that the end portions of the substrate are apart from the frame, asshown in FIG. 55 (4).

By disposing the conductive frame in such a position, it becomespossible to dispose spacers uniformly in a desired manner all over thesubstrate and prevent spacers from being disposed in a locallyconcentrated manner even in the peripheral portions of the substratewhere no transparent electrode exists, owing to the influence, frombelow, of an electric field formed by the conductive frame.

It is preferred that the above conductive stage be not greater in sizethan the substrate but large enough to cover the region outside theparting lines, and the conductive frame be formed outside so as toextend from the region outside the parting lines, to the outside of thesubstrate, as shown in FIG. 57, with the area occupied by the conductivestage and that by the conductive frame in the region outside the partinglines being [area occupied by conductive stage]>[area occupied byconductive frame].

In the above case, the conductive frame may be disposed in contact withthe substrate or out of contact with the substrate.

FIG. 59 is a schematic view illustrating the picture frame state of theblack matrix, in the method for producing a liquid crystal displaydevice according to the fifth aspect of the invention. At least one ofthe first substrate and the second substrate to be disposed opposedlyabove the first substrate is a color filter substrate for liquid crystaldisplay device production and has a black matrix formed thereon, asshown in FIG. 59. The black matrix is partitioned within the displayarea to give lattice-forming pixels.

The above black matrix defines the display area in the manner of apicture frame. That picture frame state is formed by a region where noblack matrix portion exists. In some instances, the black matrix mayremain as a solid mask or masks also in the dummy electrode portion orportions outside the picture frame. In such cases, the black matrix siteis almost identical with the region comprising transparent electrodes.

Chromium is most often used as the material for forming the black matrix(such black matrix is also called “conductive black matrix). With acolor filter substrate for liquid crystal display device productionhaving such a constitution, even when a conductive stage smaller thanthe region where a black matrix made of chromium is formed, the effectof the earthed conductive stage is obtained in the whole region of theblack matrix and the electric potential of the black matrix is lowered,so that the black matrix region can reflect the effect of the conductivestage.

Therefore, even when the conductive stage is smaller than the substrate,an electric field suited for spacer disposition is formed in the regionoccupied by the black matrix.

When, for forming the picture frame state of the black matrix on theabove substrate, a black matrix-free region is formed, the black matrixportion occurring in the display area is separated from the black matrixportion or portions in the dummy electrode region or regions outside thedisplay area, so that the effect of the earthing of the conductive stagediffers between the display area inside and the dummy electrode regionor regions.

It is therefore necessary that the size of the conductive stage be suchthat it covers the picture frame region of the black matrix, the blackmatrix-free region and the dummy electrode region or regions. When thisrequirement is satisfied, the state of spacer disposition on the wholesubstrate becomes uniform.

If, in forming the conductive frame almost on the same level as theconductive stage, as shown in FIG. 55(3), the substrate is set on theconductive frame, the substrate comes into contact with both theconductive stage upper surface and the conductive frame upper surface.

In that case, the underside (back) of the peripheral region of thesubstrate is locally exposed to the earth potential and an electricpotential from the conductive frame. In particular, in this vicinity,the black matrix within the display area is separated from the blackmatrix in the dummy electrode region or regions, so that the separatedoutside region or regions undergo a unique influence different from theeffect on the display area.

Therefore, in this case, the separated dummy electrode region or regionsshould have an electric potential close to the earth potential. For thatpurpose, it is necessary that, as shown in FIG. 57, the area occupied bythe conductive stage and that occupied by the conductive frame withinthe dummy electrode region or regions be as follows: [area occupied byconductive stage]>[area occupied by conductive frame].

If the relations between the areas occupied by the conductive stage andconductive frame within the dummy electrode region or regions becomes[area occupied by conductive stage]<[area occupied by conductive frame],the electric potential rises in each transparent electrode gap in saidregion or regions, making spacer disposition difficult.

It is preferred that the above conductive stage be not greater in sizethan the substrate but extend to the regions outside the parting lines,and that the conductive frame be formed outside the transparentelectrodes without overlapping with the regions outside the partinglines, as shown in FIG. 58.

In other words, it is required that the conductive frame be formed atplaces not included in any dummy electrode region. At such locations,the electric potential of the conductive frame will not affect the blackmatrix, hence spacers will not be locally concentrated in the peripheralregion of the substrate.

On the other hand, in cases where, among the above-mentioned positionalrelations between the conductive stage and conductive frame, theconductive frame is positioned below the conductive stage, the regionsoutside the parting lines do not directly contact with the conductiveframe, as shown in FIG. 55(4).

In that case, since the substrate end portions are not earthed, theelectric potential rises in those portions and no local spacerconcentration occurs on the substrate end portions.

In some cases, the material of the above black matrix is made of acomposition comprising a pigment dispersed in a resin, other thanchromium. Since such composition has a low conductivity, the conductivestage may fail, in certain instances, to produce the same effect asproduced in the case of a chromium black matrix.

When, in such a case, the conductive frame is disposed below thesubstrate, it is preferred that, as shown in FIG. 60, the conductivestage be almost identical in size with the region in which thetransparent electrodes exist, and that the end portions of theconductive frame be formed within the transparent electrode-free region.

In this manner, the conductive stage is caused to exist in the regioncomprising transparent electrodes to form an electric field suited forspacer disposition. On the other hand, the transparent electrode-freeregion is caused to contact with the conductive frame or to be free fromthe conductive stage, to thereby prevent the potential drop in the endportions of the substrate and thus prevent spacers from being sprayed ina locally concentrated manner.

By forming a similar electric field above the region outside the displayarea, as mentioned above, in carrying out the method for producing aliquid crystal display device according to the fifth aspect of theinvention, it becomes possible to dispose spacers uniformly all over thesubstrate, so that the liquid crystal display device obtained by thatmethod can have a uniform cell thickness and high quality displayperformance characteristics without showing display unevenness.

The method for producing a liquid crystal display device according tothe sixth aspect of the invention comprises

spraying spacers onto at least one of a first substrate comprising atleast pattern-forming transparent electrodes and an alignment layer andhaving one or more display areas and a second substrate to be disposedopposedly above the first substrate

and filling a liquid crystal into the space between both the substrates,

wherein, in spraying positively or negatively charged spacers onto thesubstrate, the substrate is disposed in close contact with an earthedconductive stage smaller in size than the substrate to allow thesubstrate periphery to be apart from the conductive stage,

and a voltage of the same polarity as the spacer charge polarity isapplied to the transparent electrodes on the substrate.

The above transparent electrodes, substrate, spacers and spacer chargingmethod are not particularly restricted but may be the same as thosementioned hereinabove referring to the first aspect of the invention.The method for producing a liquid crystal display device according tothe sixth aspect of the invention can be applied to the production ofTFT type liquid crystal display devices, as explained hereinabovereferring to the second aspect of the invention.

If, in practicing the six aspect of the present invention, a voltage ofthe same polarity as the spacer charge polarity is merely applied to thetransparent electrodes in spraying spacers, the phenomenon of the numberof spacers increasing or decreasing in the vicinity of the periphery ofthe display area is observed, as explained in detail referring to thefifth aspect of the invention, and, in the process of liquid crystaldisplay device production, the spacers undergo distortion in variousways, causing variations in cell thickness, with the result that theproduct liquid crystal display device shows display unevenness, asexplained hereinabove referring to the first and second aspects of theinvention.

Further, since a voltage of the same polarity as the spacer chargepolarity is applied to the transparent electrodes within the substrate,a repulsive force acts on spacers above the display area and, on theother hand, since the conductive stage is at the earth potential, anattractive force acts on the charged spacers and, as a result, thosespacers in the peripheral region of the substrate tend to escape fromwithin the substrate by the effects of both of the repulsive force fromwithin the substrate and the attractive force from the conductive stage,as shown in FIG. 61.

For preventing these phenomena, the sixth aspect of the inventioncomprises, in spraying positively or negatively charged spacers onto thesubstrate, disposing the substrate in close contact with an earthedconductive stage smaller in size than the substrate to thereby maintainthe peripheral region of the substrate apart from the conductive stage,as shown in FIG. 62, and applying a voltage of the same polarity as thespacer charge polarity to the transparent electrodes on the substrate.Thereby, the effect of earthing from the conductive stage upon thesubstrate end portions is weakened, and the electric potential on thetransparent electrodes tends to become rather more influential, so thatthe number of spacers to be disposed in the peripheral portions of thesubstrate can be prevented from decreasing as compared with the case inwhich the conductive stage is greater in size than the substrate.

The earthed conductive stage, the method of applying a voltage of thesame polarity as the spacer charge polarity to the transparentelectrodes formed on the substrate, the material of the conductor, theshape and size of the conductor, the method of insulating the conductivestage from the conductor, the method of voltage application to thesubstrate, the voltage values to be applied to the transparentelectrodes on the substrate and to the conductive frame, and the methodof forming the conductive frame are the same as those mentionedhereinabove referring to the fourth aspect of the invention.

The state of the peripheral region of the substrate being apart from theconductive stage is the state in which the edges of the substrate areprotruding from the conductive stage surface, as shown in FIG. 62.

Specific embodiments of the sixth aspect of the invention are nowdescribed.

The substrate onto which spacers are to be sprayed may have a blackmatrix formed thereon, as in the fifth aspect of the invention. The sameeffects as mentioned above can be obtained irrespective of whether theblack matrix is an insulating one or a conductive one.

It is preferred, however, that the black matrix is conductive, and theconductive stage comprise one or more parts each smaller in size thanthe picture frame periphery of the black matrix in each display area onthe substrate. In such a case, the number of spacers to be disposed inthe peripheral portions of the substrate can be more satisfactorilyinhibited from decreasing.

With a color filter substrate for liquid crystal display deviceproduction which has such a constitution as mentioned hereinabove indetail referring to the fifth aspect of the invention, the effect of theearthed conductive stage is produced all over the whole region of theconductive black matrix, and the electric potential on the conductiveblack matrix lowers even when a conductive stage smaller than the regionin which the conductive black matrix is formed is used. The conductiveblack matrix region can thus reflect the effect of the conductive stage.

Therefore, even when the conductive stage is smaller than the substrate,an electric field suited for spacer disposition is formed in the regionin which the conductive black matrix exists.

Since, on that occasion, that region which is outside the picture frameof the conductive black matrix is not earthed, the electric potential ofthe glass portion of the substrate is influenced by the voltage appliedto the transparent electrodes, and said electric potential rises in thedirection approaching to the electric potential of the transparentelectrodes. The state in which the region outside the picture frame ofthe conductive black matrix is not earthed is encountered, for example,when there is a portion of the black matrix but the portion is separatedfrom the picture frame by a parting line, or when there is no conductiveblack matrix portion outside the picture frame of the conductive blackmatrix.

When, in that state, the electric potential within the display area iscompared with that outside the display area, a higher electric potentialowing to the high voltage applied to the transparent electrodes and alower electric potential in each transparent electrode gap exist withinthe display area.

On the other hand, when a dummy electrode is formed, the dummy electrodeand the substrate glass portion both have a high electric potential, asshown in FIG. 63. Thus, from the whole substrate viewpoint, a highelectric potential region is formed outside the display area and a lowelectric potential region is formed within the display area.

Therefore, the high electric potential region outside the display areaserves as a wall of repulsive force and thus inhibits spacers within thedisplay area from escaping to the outside of the display area. As aresult, the number of spacers within the display area becomes uniformand the cell thickness is thereby rendered uniform, with the result thatthe product liquid crystal display device shows uniform displaycharacteristics.

Even in cases where the substrate onto which spacers are to be sprayedis a dual-panel one having a number of display areas formed thereon, thesame effects as mentioned above can be produced for all display areas,if the black matrix is conductive, by providing a plurality ofconductive stages each having a size such that each stage lies withinthe picture frame periphery of the black matrix in each display area.

In the above case, a plurality of conductive stages may respectively bedisposed corresponding to the plurality of display areas or grooves maybe formed on a single conductive stage to give a plurality of conductivestages.

The area of contact between the above conductive stage and substrate ispreferably not less than 30% of the area of the display area.

In cases where a conductive black matrix is formed as mentioned above,the conductive black matrix reflects the effect of the conductive stageeven if the conductive stage is smaller than the black matrix region. Asa result, an electric field suited for spacer disposition is formed.

However, if the area of contact between the conductive stage and displayarea (black matrix region) is too small, the effect of earthing willbecome weak. Therefore, for forming an electric field suited for spacerdisposition above the display area, the area of contact between theconductive stage and substrate should preferably be not less than 30% ofthe area of the display area on the substrate. When it is less than 30%,the effect of earthing becomes weak, the electric field suited forspacer disposition disintegrates and the spacer disposition in theperipheral region of the display area becomes difficult.

The particle sprayer according to the seventh aspect of the invention isintended for selectively disposing charged particle on a substratehaving a plurality of electrodes,

said particle sprayer comprising

a nozzle for spraying charged particles onto the substrate,

a conductive stage having a fixed position and serving to hold thesubstrate onto which charged particles are to be sprayed,

a plurality of push-up pins for mounting the substrate on anddismounting the substrate from the conductive stage, a probe forapplying a voltage identical in polarity with the charged particles to aplurality of electrodes on the substrate disposed on the conductivestage,

and a conductor electrically insulated from the conductive stage, saidconductor being a conductive frame provided with an opening smaller insize than the substrate, disposed on the top of the substrate disposedon the conductive stage and being applied a voltage of the same polarityas the charged particle polarity thereto.

The above transparent electrodes, substrate, particles and particlecharging method are the same as those mentioned hereinabove referring tothe first aspect of the invention.

The earthed conductive stage, the method of applying a voltage of thesame polarity as the spacer charge polarity to the transparentelectrodes formed on the substrate, the material of the conductor, theshape and size of the conductor, the method of insulating the conductivestage from the conductor, the method of voltage application to thesubstrate, the voltage values to be applied to the transparentelectrodes on the substrate and to the conductive frame and the methodof forming the conductive frame are the same as those mentionedhereinabove referring to the fourth aspect of the invention.

The particle sprayer according to the seventh aspect of the inventioncan be applied to the production of liquid crystal display devices and,in that case, those spacers mentioned in reference to the first aspectof the invention may be used as the particles.

Here, it is desirable that the probe and conductor can move up and downin synchronization with each other or integrally with each other and/or,further, that the probe, conductor and push-up pins can be driven insynchronization with one another by a single driving mechanism.

It is preferred that one and the same voltage is applied to theplurality of electrodes and the conductor simultaneously.

Specific embodiments of the seventh aspect of the invention as appliedto the production of liquid crystal display devices are now describedreferring to FIGS. 64 to 68.

FIG. 64 shows a schematic sectional view of an example of the particlesprayer according to the seventh aspect of the invention, FIG. 65 is anexplanatory view showing the manner of feeding and carrying-out of thesubstrate in operating the sprayer shown in FIG. 64, FIG. 66 is anenlarged explanatory view of the essential parts of the sprayer shown inFIG. 64, and FIG. 67 is an explanatory plan view showing the relationbetween the substrate and conductive frame.

As shown in FIG. 64, the particle sprayer comprises a particle tank 11 bfor feeding spacers, which are particles to be sprayed onto a substrate,together with an air flow, a pipe 17 for carrying, by means of an airflow, the spacers supplied by the particle tank 11 b to thereby causethe spacers to be charged as a result of their contacting with the pipeinside wall on the way to the site of spraying, a chamber 10 forspraying the spacers onto the substrate. The chamber 10 has, at itslower part, a driving mechanism 31 for driving a conductive frame, aprobe, push-up pins and so forth, which are to be described laterherein, in the vertical direction and, on its side, a robot mechanism 32for feeding the substrate onto which spacers are to be sprayed into thechamber 10 and taking out the substrate having spacers sprayed thereonfrom within the chamber 10.

The chamber 10 is equipped, at its top, with a nozzle 11 a for sprayingthe charged spacers fed through the pipe 17 from the particle tank 11 buniformly over a predetermined spacer spraying range 33 while swingingand, at its lower part, with a conductive stage 15 for holding thesubstrate 1 for liquid crystal display device production as mountedthereon. This conductive stage 15 is disposed at a fixed positionrelative to the chamber 10, and the spacers sprayed from the nozzle 11 afall onto and are disposed on the substrate 1 held by the top surface ofthe conductive stage.

The conductive stage 15 holds the substrate 1 placed thereon and, abovethis substrate 1, there is disposed vertically movably a conductiveframe 34 which is to be overlapped and laid on the upper surface of thesubstrate 1. This conductive frame 34 is a thin plate-like conductor ora thin plate-like body coated with a conductive material and has a sizesufficiently greater than the spacer spraying range 33 of the nozzle 11a and has an opening 34 a, which is greater than the display area of thesubstrate 1 but smaller than the substrate 1 for exposing the displayelectrode domain comprising the transparent electrodes 3 on thesubstrate 1, as shown in FIG. 67.

It is preferred that this opening 34 a be greater than the display areaof a liquid crystal display device produced from the substrate 1 andother parts but be smaller than the dummy electrode region formedoutside the display electrode region comprising display electrodes 3 forproducing an antistatic effect, among others.

Above the conductive frame 34, there is a probe 35 which is movable upand down in synchronization with the conductive frame 34 and presses itstip or point to a transparent electrode 3 (preferably a dummy electrode)on the substrate 1 and thereby applies a voltage to the transparentelectrodes 3. This probe 35 is connected, together with the conductiveframe 34, with a voltage application apparatus 12 (cf. FIG. 64) andserves to apply a predetermined voltage having the same polarity as thespacer charge polarity to the transparent electrodes 3 on the substrate1 and conductive frame 34.

Here, a force is preferably exerted on the probe 35 in a downwarddirection by means of a spring (not shown) so that the probe may stablycontact with a transparent electrode 3 on the substrate 1. When adownward force is exerted on it, it may be fixed to the conductive frame34, as shown in FIG. 66, or, when the same voltage is applied to theconductive frame 34 and the transparent electrodes 3 on the substrate 1,a conductor connector (not shown) may be provided as the probe 35, whichis connected with the transparent electrodes 3 on the substrate 1disposed in contact with the lower surface of the conductive frame 34.

For feeding the substrate 1 to be mounted on and held by the uppersurface of the conductive stage 15 or taking out the substrate 1, aplurality of push-up pins 36 extending through the conductive stage 15are provided so that they may push up the substrate 1 and enableinsertion of arms 32 a of the robot mechanism 32, as shown in FIG. 65.

These push-up pins 36 push up the substrate 1 and enable insertion ofthe arms 32 a of the robot mechanism 32 and, further, peel the substrate1 from the conductive stage 15 electrostatically kept in intimatecontact therewith by the voltage applied in spacer spraying by thenozzle 11 a while introducing air from the surroundings of thesubstrate. Preferably, those pins which push up the periphery of thesubstrate have a slightly greater length and those pins which push upthe middle of the substrate have a slightly shorter length so that airintroduction from around the periphery of the substrate may befacilitated.

For facilitating the peeling of the substrate 1 from the conductivestage 15, it is also possible to provide the conductive stage 15 withair holes (not shown) and feed air to between the conductive stage 15and substrate 1 therethrough. In that case, it is no more necessary tomake those push-up pins 36 on the substrate periphery longer.

By providing such air holes, it is also possible to facilitate thepeeling of the substrate 1 by blowing air therethrough in pushing up thesubstrate 1 by means of the push-up pins 36 after bring the substrate 1into intimate contact with the conductive stage by evacuationtherethrough in mounting and holding the substrate 1 on the uppersurface of the conductive stage 15.

The push-up pins 36 and conductive frame 34 are connected with thesingle driving mechanism 31. In accordance with the seventh aspect ofthe invention, this driving mechanism 31 is a flat plate-like onedisposed below the conductive stage 15. When this flat plate-likedriving mechanism 31 is moved up and down by means of a driving source(not shown), the push-up pins 36 and conductive stage 34 move up anddown accordingly.

In feeding the substrate 1 or taking out the same, it is necessary tofirst raise the conductive frame 34 to make it possible to raise thepush-up pins 36 and then raise the push-up pins 36 to thereby peel andlift the substrate 1 off from the conductive stage 15.

For this purpose, according to the seventh aspect of the invention,measures are taken so that a gap A may be formed between the substrate 1and push-up pins 36 when the driving mechanism 31 is in its descendedstate, as shown in FIG. 66. Thus, when the driving mechanism 31 israised, the conductive frame 34 alone is raised in the beginning and,after the rise of the conductive frame 34 by the gap A, the push-up pinsrise to contact with the substrate 1 and then peel off the same from theconductive stage 15 and lift the same.

By separating, in the above manner, the substrate 1 from the conductiveframe 34 by the gap A in the raised state of the driving mechanism 31, asufficient gap is secured to slightly raise the arms 32 a so that thesubstrate 1 may be out of contact with the push-up pins 36 in the stepof feeding or taking out the substrate 1 by means of the robot mechanism32.

A typical example of the layout of the push-up pins 36, the push-upshafts 34 b of the conductive frame 34 and the arms 32 a of the robotmechanism 32 is shown in FIG. 67. As shown in FIG. 67, a number ofpush-up pins 36 are preferably provided so that the substrate 1 may notbe damaged in the step of peeling the substrate 1 off from theconductive stage 15.

The push-up shafts 34 b of the conductive frame 34 are desirablydisposed around the substrate 1 or conductive stage 15 so that they maynot interfere with the latter. The arms 32 a of the robot mechanism 32are drawn by imaginary lines on the left of FIG. 67. The arms 32 aformed as a plurality of branches so that they may not interfere withthe push-up pins 36 or with the push-up shafts 34 b of the conductiveframe 34 are provided with sucking cups 32 b for sucking and holding thesubstrate 1.

FIG. 68 is an explanatory view showing an equipotential line 37 observedwhen a voltage is applied to the conductive frame 34 and the transparentelectrodes 3 on the substrate 1. As shown in FIG. 68, the electricpotential is higher above the conductive frame 34 and transparentelectrodes 3 and it is lower in each gap between electrodes(interelectrode gap), namely in each gap between neighboring transparentelectrodes and in each gap between the conductive frame 34 and theneighboring transparent electrode 3.

Since the spacers sprayed from the nozzle 11 a are charged and have thesame polarity as the polarity of the voltage applied to the conductiveframe 34 and transparent electrode domain 3, the spacers fall whilebeing repelled by the repulsive force exerted by the electric fieldabove the substrate, move toward the positions where the electricpotential is low, and drop concentratedly in interelectrode gaps, namelythe gaps between respective transparent electrodes and gaps between theconductive frame 34 and the respective neighboring transparentelectrodes 3.

In the region outside the conductive frame 34, which are far away fromthe spacer spraying range 33, no spacer drops outside the conductiveframe 34 even if there is repulsion by a repulsive force. The spacerssprayed from the nozzle 11 a thus fall only onto the transparentelectrode gaps and the gaps between the conductive frame 34 and therespective neighboring transparent electrodes 3.

The voltages to be applied to the conductive frame 34 and transparentelectrodes 3 can be selected so that spacers fall onto the transparentelectrode gaps and the gaps between the conductive frame 34 and therespective neighboring transparent electrodes 3 with an appropriateprobability. By selecting one and the same voltage and selecting the gapdistance between the neighboring transparent electrodes 3 and betweenthe conductive frame 34 and the neighboring transparent electrodes 3 sothat spacers may fall therein with an appropriate probability, it ispossible, in gradually applying the voltage to or removing the same fromthe transparent electrodes 3 on the substrate 1 and the conductive frame34, to simultaneously apply the voltage to them or remove the sametherefrom and thus facilitate the voltage control on the power sourceapparatus 12.

Some typical embodiments of the seventh aspect of the invention havebeen described above. It is to be noted, however, that the seventhaspect of the invention is not limited to these embodiments but variousmodifications and variations can of course be made without departingfrom the spirit of the seventh aspect of the invention.

The eighth aspect of the invention is related to the liquid crystaldisplay device produced by using the method of spraying particlesaccording to the first aspect of the invention.

The ninth aspect of the invention is related to the liquid crystaldisplay device produced by the method for producing a liquid crystaldisplay device according to the second or third aspect of the invention.

The tenth aspect of the invention is related to the liquid crystaldisplay device produced by the method for producing a liquid crystaldisplay device according to the fourth, fifth or sixth aspect of theinvention while using the particle sprayer according to the seventhaspect of the invention.

The liquid crystal display device according to the eighth, ninth ortenth aspect of the invention is uniform in cell thickness and show highquality display characteristics without display unevenness.

BEST MODES FOR CARRYING OUT THE INVENTION

The following examples illustrate the present invention in furtherdetail. They are, however, by no means limitative of the scope of theinvention.

EXAMPLE 1

A pair of soda glass-made insulating substrates each having an outersize of 370×480 mm and a thickness of 0.7 mm were used. On one of theinsulating substrates 1, there were formed RGB color filters 4 with ablack matrix 5, which is a light shielding layer, and an overcoat 6 forprotecting the color filters 4. On the overcoat 6 were formedstripe-shaped display electrodes 3 made of ITO and further an alignmentlayer 9 made of a polyimide resin. After alignment treatment, a sealingmaterial 24 was applied by the technique of screen printing. Glass beadsto serve as spacers 25 within the sealing material was incorporated inthe sealing material 24.

On the other insulating substrate 1, there were formed, as shown in FIG.5 and FIG. 69, 285-μm-wide stripe-shaped display electrodes 3 made ofITO and having a thickness of 300 nm at intervals of 15 μm. Auxiliaryelectrodes 20 were further formed for voltage application to the displayelectrodes 3, dummy electrodes 21 were formed along the sides wherethere was no auxiliary electrode 20 and, further, an insulating layer 23and an alignment layer 9 made of a polyimide resin were formed. In someinstances, the insulating layer 23 need not be formed.

Here, the dummy electrodes 21 were electrically connected together bymeans of a conductive material (effective in reducing the number ofpower supplying parts). In FIG. 69, dummy electrodes 21 are disposedonly along the upper, lower and right sides of the effective displayarea. This is because there are the auxiliary electrodes 20 for voltageapplication to the display electrodes outside the left side of theeffective display area and this produces the same effect as the dummyelectrodes 21 produces.

Using synthetic resin particles, BBS-60510-PH (product of Sekisui FineChemical), as spacers, these were charged negatively and sprayed ontosaid other insulating substrate 1. On that occasion, a voltage of −2 kVwas applied to the display electrodes 3 and to the dummy electrodes 21(cf. FIG. 5).

As a result, spacers 8 could be disposed only in the gaps betweendisplay electrodes 3. The selectivity of disposition of spacers 8 ininterelectrode gaps was improved as compared with the case in which nodummy electrode 21 was provided.

Then, the insulating substrates 1 forming a pair were lapped over eachother, hot-pressed at 180° C. and 0.8 kg/cm² and post-baked at 150° C.Thereafter, trimming was performed for removing unnecessary portions,whereupon the auxiliary electrodes 20 and dummy electrodes 21 were cutoff. Then, a liquid crystal 7 was poured therebetween to give a liquidcrystal display device (shown in FIG. 70) in which the pair ofinsulating substrates were bonded together.

EXAMPLE 2

A pair of soda glass-made insulating substrates each having an outersize of 370×480 mm and a thickness of 0.7 mm were used. On one of theinsulating substrates 1, there were formed RGB color filters 4 with ablack matrix 5, which is a light shielding layer, and an overcoat 6 forprotecting the color filters 4. On the overcoat 6 were formedstripe-shaped display electrodes 3 made of ITO and further an alignmentlayer 9 made of a polyimide resin. After alignment treatment, a sealingmaterial 24 was applied by the technique of screen printing. Glass beadsto serve as spacers 25 within the sealing material was incorporated inthe sealing material 24.

On the other insulating substrate 1, there were formed, as shown in FIG.11 and FIGS. 13-16, 285-μm-wide stripe-shaped display electrodes 3 a and3 b made of ITO and having a thickness of 300 nm at intervals of 15 μm.Auxiliary electrodes 20 a and 20 b and accessory electrodes 29 wereformed and, further, an insulating layer 23 and an alignment layer 9made of a polyimide resin were formed. The insulating layer 23 need notbe formed in some instances.

Using synthetic resin particles, BBS-60510-PH (product of Sekisui FineChemical), as spacers, these were charged negatively and sprayed ontosaid other insulating substrate 1. On that occasion, a voltage of −500 Vwas applied to the display electrodes 3 a and −700 V to the displayelectrodes 3 b, to produce a potential difference of 200 V between thedisplay electrodes 3 a and 3 b. The same voltage as that applied to thedisplay electrodes 3 b, namely −700 V, was applied to the accessoryelectrodes 29 (cf. FIG. 11 and FIGS. 13-16).

As a result, spacers 8 could be disposed only in the gaps betweendisplay electrodes 3 a and the density of spacers disposed in the gapsbetween display electrodes 3 a, inclusive of those gaps between displayelectrodes 3 a in the vicinity of the periphery of each display area 30,could be rendered uniform within the display area 30.

Furthermore, spacers 8 could be disposed concentratedly in the middle ofeach gap between display electrodes 3 a and the probability of spacers 8being disposed in the edge portions of the display electrodes 3 a couldbe reduced.

Then, the insulating substrates 1 forming a pair were lapped over eachother, hot-pressed at 180° C. and 0.8 kg/cm² and post-baked at 150° C.Thereafter, trimming was performed for removing unnecessary portions,whereupon the auxiliary electrodes 20 a and 20 b and accessoryelectrodes 29 were cut off. Then, a liquid crystal 7 was pouredtherebetween to give a liquid crystal display device (shown in FIG. 70)in which the pair of insulating substrates were bonded together.

EXAMPLE 3

Spacers 8 were sprayed in the same manner as in Example 2 except that+500 V was applied to the display electrodes 3 a and +300 V to thedisplay electrodes 3 b on the other insulating substrate 1, to give apotential difference of 200 V between the display electrodes 3 a and 3 bwhile the same voltage as applied to the display electrodes 3 a (+500 V)was applied to the accessory electrodes 29 (cf. FIG. 11 and FIGS.17-20).

As a result, spacers 8 could be disposed only in the gaps betweendisplay electrodes 3 a, and the density of spacers disposed in the gapsbetween display electrodes 3 a, inclusive of those gaps between displayelectrodes 3 a in the vicinity of the periphery of each display area 30,could be rendered uniform within the display area 30.

Thereafter, a liquid crystal display device was manufactured in the samemanner as in Example 2.

EXAMPLE 4

Spacers 8 were sprayed in the same manner as in Example 2 except that+50 V was applied to the display electrodes 3 a and −150 V to thedisplay electrodes 3 b on the other insulating substrate 1, to give apotential difference of 200 V between the display electrodes 3 a and 3 bwhile −100 V was applied to the accessory electrodes 29 by connecting aconductor wire 18 therewith (cf. FIG. 12, FIG. 17 and FIGS. 21-23).

As a result, spacers 8 could be disposed only in the gaps betweendisplay electrodes 3 a and the density of spacers disposed in the gapsbetween display electrodes 3 a, inclusive of those gaps between displayelectrodes 3 a in the vicinity of the periphery of each display area 30,could be rendered uniform within the display area 30.

Thereafter, a liquid crystal display device was manufactured in the samemanner as in Example 2.

EXAMPLE 5

Spacers 8 were sprayed in the same manner as in Example 2 except that+150 V was applied to the display electrodes 3 a and −50 V to thedisplay electrodes 3 b on the other insulating substrate 1, to give apotential difference of 200 V between the display electrodes 3 a and 3 bwhile +100 V was applied to the accessory electrodes 29 by connecting aconductor wire 18 therewith (cf. FIG. 12, FIG. 17 and FIGS. 24-26).

As a result, spacers 8 could be disposed only in the gaps betweendisplay electrodes 3 a and the density of spacers disposed in the gapsbetween display electrodes 3 a, inclusive of those gaps between displayelectrodes 3 a in the vicinity of the periphery of each display area 30,could be rendered uniform within the display area 30.

Thereafter, a liquid crystal display device was manufactured in the samemanner as in Example 2.

EXAMPLE 6

Spacers 8 were sprayed in the same manner as in Example 2 except that+50 V was applied to the display electrodes 3 a and −150 V to thedisplay electrodes 3 b on the other insulating substrate 1, to give apotential difference of 200 V between the display electrodes 3 a and 3 bwhile −100 V was applied to the accessory electrodes 29 by connecting aconductor wire 18 therewith (cf. FIGS. 27-31).

As a result, spacers 8 could be disposed only in the gaps betweendisplay electrodes 3 a and the density of spacers disposed in the gapsbetween display electrodes 3 a, inclusive of those gaps between displayelectrodes 3 a in the vicinity of the periphery of each display area 30,could be rendered uniform within the display area 30.

Thereafter, a liquid crystal display device was manufactured in the samemanner as in Example 2.

EXAMPLE 7

Spacers 8 were sprayed in the same manner as in Example 2 except that−300 V was applied to the display electrodes 3 a and accessoryelectrodes 29 a and −500 V to the display electrodes 3 b and accessoryelectrodes 29 b on the other insulating substrate 1, to give a potentialdifference of 200 V between the display electrodes 3 a and 3 b (cf.FIGS. 32-35).

As a result, spacers 8 could be disposed only in the gaps betweendisplay electrodes 3 a and the density of spacers disposed in the gapsbetween display electrodes 3 a, inclusive of those gaps between displayelectrodes 3 a in the vicinity of the periphery of each display area 30,could be rendered uniform within the display area 30.

Thereafter, a liquid crystal display device was manufactured in the samemanner as in Example 2.

EXAMPLE 8

Spacers 8 were sprayed in the same manner as in Example 2 except that+300 V was applied to the display electrodes 3 a and +500 V to thedisplay electrodes 3 b on the other insulating substrate 1, to give apotential difference of 200 V between the display electrodes 3 a and 3 bwhile the same voltage as applied to the display electrodes 3 b (+500 V)was applied to the accessory electrodes 29 (cf. FIG. 11, FIG. 17 andFIGS. 36-38).

As a result, spacers 8 could be disposed only in the gaps betweendisplay electrodes 3 a and the density of spacers disposed in the gapsbetween display electrodes 3 a, inclusive of those gaps between displayelectrodes 3 a in the vicinity of the periphery of each display area 30,could be rendered uniform within the display area 30.

Furthermore, spacers 8 could be disposed concentratedly in the middle ofeach gap between display electrodes 3 a and the probability of spacers 8being disposed in the edge portions of the display electrodes 3 a couldbe reduced.

Thereafter, a liquid crystal display device was manufactured in the samemanner as in Example 2.

EXAMPLE 9

A common electrode substrate (substrate having a sheet thickness of 0.7mm with color filters formed thereon; aperture of each of RGBpixels=80×285 μm, black matrix line width=20 μm, ITO electrode width=290μm, electrode gap distance=15 μm) for STN type liquid crystal displaydevice production, as shown in FIG. 45, was prepared (after spacerdisposition and the subsequent cutting off of the conductor lines,giving a common electrode substrate like the conventional one).

A 0.05-μm-thick polyimide alignment layer was formed on this substrateand subjected to rubbing treatment.

A spacer sprayer, such as shown in FIG. 71, was used as the sprayer. Anantistatic mat having a surface resistance of not more than 10⁷ Ωcm waslaid in intimate contact with an earthed conductive stage made ofaluminum and disposed in the lower part of the sprayer body, and thesubstrate was disposed thereon in close contact with the mat. Twoconnecting terminals for voltage application connected with a voltageapplication apparatus were provided within the sprayer and wires wereintroduced into the sprayer so that different direct current voltagesmight be applied to the transparent electrodes formed on the substrate.

Micropearl BB-6.8 μm-PH (trademark; product of Sekisui Fine Chemical)particles were prepared as spacers.

Then, the terminals for voltage application were connected with a powersource and a voltage of −2.7 kV was applied to each dual conducting part(conducting line (A)) of 2:1 type comb-shaped electrodes and a voltageof −2.8 kV to each other conducting part (conducting line (B)).

Then, the conducting part (conducting line (A)) to which the voltage of−2.7 kV was applied was connected with each dummy electrode by wiring sothat all dummy electrodes might have the same electric potential (inFIG. 45, the conducting line (A) was further connected with the dummyelectrodes by wiring).

While maintaining this state, the spacers were passed through astainless steel pipe capable of charging them negatively (−) and sprayedonto the substrate by means of compressed air. That the spacers werenegatively charged on that occasion had been confirmed beforehand.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed at black matrixsites in each gap between the two neighboring electrodes involvedtherein to which the voltage of −2.7 kV had been applied, uniformly allover the substrate.

COMPARATIVE EXAMPLE 1

The procedure of Example 9 was followed in the same manner except thatno voltage was applied to the dummy electrodes.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed at black matrixsites in each gap between the two neighboring electrodes involvedtherein to which the voltage of −2.7 kV had been applied but that therewere marked decreases in the number of spacers in the peripheral regionfrom the periphery of each display area to a line about 10 mm insidesaid periphery.

EXAMPLE 10

The procedure of Example 9 was followed in the same manner except thatthe substrate used had 2:1 type comb-shaped electrodes each singleconducting part (conducting line (B)) of which was connected with thedummy electrodes, as shown in FIG. 44, and that a voltage of −2.7 kV wasapplied to each dual conducting part (conducting line (A)) of the 2:1type comb-shaped electrodes, and a voltage of −2.8 kV to each otherconducting part (conductor line (B)).

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed at black matrixsites in each gap between the two neighboring electrodes involvedtherein to which the voltage of −2.7 kV had been applied, uniformly allover the substrate.

EXAMPLE 11

The procedure of Example 9 was followed in the same manner except thatthe dummy electrodes were connected respectively and a voltage of −2.75kV was applied thereto using a separate voltage application apparatus.

Observation of the substrate with the spacers sprayed thereon under thelight-microscope revealed that the spacers were disposed at black matrixsites in each gap between the two neighboring electrodes involvedtherein to which the voltage of −2.7 kV had been applied, uniformly allover the substrate.

EXAMPLE 12

A common electrode substrate (substrate having a glass thickness of 0.7mm with color filters formed thereon; aperture of each of RGBpixels=80×285 μm, metallic chromium-made black matrix line width=35 μm,acrylic resin overcoat layer=3.0 μm, ITO electrode width=290 μm,electrode gap distance=25 μm) for STN type liquid crystal display deviceproduction was prepared as the substrate.

A 0.05-μm-thick polyimide alignment layer was formed on this substrateand subjected to rubbing treatment.

The ITO electrodes were formed as shown in FIG. 3.

A spacer sprayer, such as shown in FIG. 71, manufactured by NisshinEngineering was used as the sprayer. Prepared as the spacers wereMicropearl BB, 7.25 μm-PH (trademark; product of Sekisui Fine Chemical)particles.

An earthed aluminum stage and an aluminum conductive frame were disposedwithin the sprayer, as shown in FIG. 46. The stage was insulated fromthe conductive frame by a butyl rubber type resin, and measures weretaken so that voltage application might be made to both the ITO displayelectrodes and dummy electrodes, as shown in FIG. 50. Each probe usedhad a size sufficient to exert a pressure on several electrodes.

By applying −2.0 kV to the conductive frame by means of a voltageapplication apparatus, the same voltage of −2.0 kV as applied to thedummy electrodes and ITO display electrodes.

While maintaining the above state, the spacers were sprayed onto thesubstrate. The spacers were negatively (−) charged upon spraying.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps (black matrix sites) and, even in the peripheral display area, theywere disposed uniformly.

EXAMPLE 13

The spacers were sprayed in the same manner as in Example 12 except thata substrate having such a structure as shown in FIG. 2 in which thedummy electrode and display electrodes were connected together was usedin lieu of the substrate used in Example 12, that the constitution ofthe stage and conductive frame was as shown in FIG. 46 and that thevoltage application from the conductive frame to the dummy electrode wascarried out in the manner shown in FIG. 49.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps (black matrix sites) and, even in the peripheral display area, theywere disposed uniformly.

EXAMPLE 14

The stage and conductive frame were constituted as shown in FIG. 47, asubstrate having such an electrode structure as shown in FIG. 2 wasused, a terminal derived from a voltage application apparatus wasconnected with the dummy electrode, and −2.0 kV was applied to the ITOdisplay electrodes and dummy electrode.

Separately, a voltage of −2.7 kV was applied to the conductive frameusing another power source. While maintaining this state, the spacerswere sprayed as mentioned in Example 12.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps (black matrix sites) and, even in the peripheral display area, theywere disposed uniformly.

COMPARATIVE EXAMPLE 2

In Example 12, no conductive frame was used and the substrate wasdisposed directly on the stage so that voltage application might be madeonly to the ITO display electrodes by means of rod-shaped electrodes.Thus, −2.0 kV was applied thereto. In that state, the spacers weresprayed in the same manner as in Example 12.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps in the middle region of the substrate but no spacers were found inthe peripheral zone (about 30 mm wide) of the display area.

EXAMPLE 15

A common electrode substrate (substrate having a glass thickness of 0.7mm with color filters formed thereon; aperture of each of RGBpixels=80−285 μm, metallic chromium-made black matrix line width=35 μm,acrylic resin overcoat layer=3.0 μm, ITO electrode width=290 μm,electrode gap distance=25 μm) for STN type liquid crystal display deviceproduction was prepared as the substrate.

A 0.05-μm-thick polyimide alignment layer was formed on this substrateand subjected to rubbing treatment.

The ITO electrodes were formed as shown in FIG. 2 and measures weretaken, as shown in FIG. 72, so that a voltage might be applied to allITO electrodes on the substrate by applying the voltage to the dummyelectrode.

A Nisshin Engineering model DISPA-μR (trademark) sprayer was used as thesprayer and, as shown in FIG. 73, chromium foil sections were providedon a flat vinyl chloride resin plate within the sprayer, the middlesection, which was serve as the conductive stage, was earthed, aconductive frame was formed around the same and a terminal derived froma voltage application apparatus was connected with a part thereof sothat voltage supply might be made via that terminal.

The positional relations among the substrate, stage and conductive framewere as shown in FIG. 57. Thus, the conductive stage was smaller in sizethan the substrate but was large enough to reach the inside of the dummyelectrode domain (region outside the trimming lines), the conductiveframe was formed from within the dummy electrode domain to the outsideof the substrate, and the area occupied by the conductive stage and thatoccupied by the conductive frame within the dummy electrode domain wereas follows: [area of conductive stage]>[area of conductive frame].Further, a state was produced in which the substrate end portionunderside was in contact with the conductive frame.

Prepared as the spacers were Sekisui Fine Chemical's Micropearl BB-PH(trademark), 7.25 μm in particle size.

Then, −2.0 kV was applied to the dummy electrode and ITO electrodes byapplying −2.0 kV to the conductive frame by means of a voltageapplication apparatus and, while maintaining this state, the spacerswere sprayed onto the substrate. The negative charging of the spacershad been confirmed beforehand.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps, namely at black matrix sites. Furthermore, the spacers wereuniformly disposed in the peripheral area of the display area as well.

Thereafter, this substrate was used to complete a liquid crystal displaydevice in the conventional manner. The thus-completed liquid crystaldisplay device showed high contrast owing to the absence of spacers atpixel sites, and showed good display performance characteristics withgood display evenness owing to the spacer disposition all over thesubstrate, unlike the cases of spacer spraying by the conventionalmethods of liquid crystal display device production.

EXAMPLE 16

The procedure of Example 15 was followed in the same manner except thatthe conductive stage and conductive frame were made of separatestainless steel plates. The conductive frame was fixed within thesprayer by means of Teflon-made supporting rods, and the conductivestage and the conductive frame were insulated from each other by air.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps, namely at black matrix sites. Furthermore, the spacers wereuniformly disposed in the peripheral area of the display area as well.

Thereafter, this substrate was used to complete a liquid crystal displaydevice in the conventional manner. The thus-completed liquid crystaldisplay device showed high contrast owing to the absence of spacers atpixel sites, and showed good display performance characteristics withgood display evenness owing to the spacer disposition all over thesubstrate, unlike the cases of spacer spraying by the conventionalmethods of liquid crystal display device production.

EXAMPLE 17

The procedure of Example 15 was followed in the same manner except thatthe positional relations among the substrate, stage and conductive framewere as shown in FIG. 58. Thus, the conductive stage was smaller in sizethan the substrate but sufficiently enough to reach the inside of thedummy electrode domain (region outside the trimming lines), theconductive frame was formed outside the dummy electrode withoutoverlapping with the same and, further, a state was produced in whichthe substrate end portion underside was in contact with the conductiveframe.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps, namely at black matrix sites. Furthermore, the spacers wereuniformly disposed in the peripheral area of the display area as well.

Thereafter, this substrate was used to complete a liquid crystal displaydevice in the conventional manner. The thus-completed liquid crystaldisplay device showed high contrast owing to the absence of spacers atpixel sites, and showed good display performance characteristics withgood display evenness owing to the spacer disposition all over thesubstrate, unlike the cases of spacer spraying by the conventionalmethods of liquid crystal display device production.

EXAMPLE 18

The procedure of Example 15 was followed in the same manner except thatthe black matrix formed on the substrate was made of a resin and thatthe positional relations among the substrate, stage and conductive framewere as shown in FIG. 60. Thus, the size of the conductive stage wassubstantially identical with the domain in which the transparentelectrodes were present, the conductive frame was formed from a regionwhere there was no transparent electrode and, further, the substrate endportion underside was in contact with the conductive frame.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps, namely at black matrix sites. Furthermore, the spacers wereuniformly disposed in the peripheral area of the display area as well.

Thereafter, this substrate was used to complete a liquid crystal displaydevice in the conventional manner. The thus-completed liquid crystaldisplay device showed high contrast owing to the absence of spacers atpixel sites, and showed good display performance characteristics withgood display evenness owing to the spacer disposition all over thesubstrate, unlike the cases of spacer spraying by the conventionalmethods of liquid crystal display device production.

COMPARATIVE EXAMPLE 3

The procedure of Example 16 was followed in the same manner except thatthe conductive stage was made of stainless steel but the size thereofremained the same and that the conductive frame was removed to give aconductive frame-free state.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps in the middle region of the substrate but no spacers were found inthe peripheral zone (about 30 mm wide) of the display area.

Thereafter, this substrate was used to complete a liquid crystal displaydevice in the conventional manner. The thus-completed liquid crystaldisplay device showed high contrast display characteristics in thecentral portion of the substrate but showed display unevenness owing tothe fact that the cell thickness had been reduced in the peripheralregion of the substrate.

EXAMPLE 19

The procedure of Example 15 was followed in the same manner except thatthe conductive frame was disposed over an area extending to the displayarea inside, that the substrate end portion underside was in contactwith the conductive frame and that the conductive stage was smaller thanthe conductive frame.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps in small numbers and disposed also on pixels in large numbers.

Thereafter, this substrate was used to complete a liquid crystal displaydevice in the conventional manner. The thus-completed liquid crystaldisplay device was inferior in contrast to that obtained in Example 15.

EXAMPLE 20

A common electrode substrate (substrate having a glass thickness of 0.7mm with color filters formed thereon; aperture of each of RGBpixels=80×280 μm, resin-made black matrix line width=35 μm, acrylicresin overcoat layer=3.0 μm, ITO electrode width=290 μm, electrode gapdistance=25 μm) for STN type liquid crystal display device productionwas prepared as the substrate.

A 0.05-μm-thick polyimide alignment layer was formed on this substrateand subjected to rubbing treatment.

The substrate used was a dual panel substrate having two display areasformed on one substrate.

The ITO electrodes were formed to leave a margin of about 10 mm fromeach edge of the substrate and in a manner such that voltage applicationto the dummy electrode might result in voltage application to all ITOelectrodes on the substrate, as shown in FIG. 2.

A Nisshin Engineering model DISPA-μR (trademark) sprayer, as shown inFIG. 74, was used as the sprayer and, as shown in FIG. 62, theconductive stage was almost identical in size with the ITO electrodedomain on the substrate, hence the periphery thereof was about 10 mminside from each substrate edge.

Sekisui Fine Chemical's Micropearl BB-PH (trademark) particles, 7.25 μmin particle size, were prepared as the spacers.

Then, a direct current source-derived terminal was connected with thedummy electrode on the substrate and −2.0 kV was applied to all ITOelectrodes on the substrate and, while maintaining this state, thespacers were sprayed onto the substrate. The negative charging of thespacers had been confirmed beforehand.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps, namely at black matrix sites.

Thereafter, this substrate was used to complete a liquid crystal displaydevice in the conventional manner. The thus-completed liquid crystaldisplay device showed high contrast owing to the absence of spacers atpixel sites, and showed good display performance characteristics withgood display evenness owing to the spacer disposition all over thesubstrate, unlike the cases of spacer spraying by the conventionalmethods of liquid crystal display device production.

EXAMPLE 21

The procedure of Example 20 was followed in the same manner except thata chromium black matrix with a line width of 35 μm was used as the blackmatrix, and that the conductive stage used had been divided into twoparts corresponding to the two display areas on the substrate,respectively, with the periphery of each part being 5 mm inside theblack matrix picture frame.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps, namely at black matrix sites.

Thereafter, this substrate was used to complete a liquid crystal displaydevice in the conventional manner. The thus-completed liquid crystaldisplay device showed high contrast owing to the absence of spacers atpixel sites, and showed good display performance characteristics withgood display evenness owing to the spacer disposition all over thesubstrate, unlike the cases of spacer spraying by the conventionalmethods of liquid crystal display device production.

COMPARATIVE EXAMPLE 4

Spacer spraying was carried out in the same manner as in Example 20except that the conductive stage used had a size greater by 50 mm thanthe substrate.

Observation of the substrate with the spacers sprayed thereon under thelight microscope revealed that the spacers were disposed in electrodegaps, namely at black matrix sites, but few spacers were found in theperipheral zone (about 30 mm wide) of the display area.

Thereafter, this substrate was used to complete a liquid crystal displaydevice in the conventional manner. The thus-completed liquid crystaldisplay device showed high contrast and good display characteristics inthe central portion of the display area but, in the peripheral region ofthe display area showed display unevenness because of a reduced cellthickness owing to the absence of spacers.

EXAMPLE 22

Spacer spraying was carried out in the same manner as in Example 21except that the conductive stage used had a size of 40%, 30% or 20% ofthe display area.

After observation of the substrates with the spacers sprayed thereonunder the light microscope, these substrates were used to completeliquid crystal display devices in the conventional manner.

When the conductive stage having a size of 40% of the display area wasused, the spacers were disposed in electrode gaps, namely at blackmatrix sites, like in Example 21, and the liquid crystal display devicecompleted showed high contrast owing to the absence of spacers at pixelsites and had good display performance characteristics with displayevenness owing to the spacer disposition all over the display area.

When the conductive stage having a size of 30% of the display area wasused, some spacers were disposed in pixel sites but the liquid crystaldisplay device completed showed little influence on the contrast andshowed high contrast since the number of spacers disposed in the pixelsites was small.

When the conductive stage having a size of 20% of the display area wasused, the spacers were disposed almost randomly on the display area andthe liquid crystal display device completed showed no improvement incontrast.

EXAMPLE 23

Using a particle sprayer as shown in FIG. 64-67, a substrate 1 ontowhich spacers were to be sprayed was first fed onto the conductive stage15. For feeding the substrate 1, the substrate 1 was taken out of asubstrate stock site (not shown) by means of arms 32 a of a robotmechanism 32 and, at the same time, a drive mechanism 31 ascended andraised the push-up pins 36 and conductive frame 34 for producing a gapfor insertion of the substrate 1 between the push-up pins 36 andconductive frame 34.

Then, the lid 10 a of an opening provided at a chamber 10 site facingthe robot mechanism 32 was opened and the arms 32 a of the robotmechanism 32 were inserted into the chamber and further advanced toinsert the substrate 1 between the push-up pins 36 and conductive frame34. Thereafter, the push-up pins 36 and conductive frame 34 descended,whereby the substrate 1 was fed onto and disposed on the conductivestage 15. The conductive frame 34 further descended and was disposed andheld on the conductive stage 15.

On that occasion, the probe 35 also descended with the conductive frame34 and the tip of the probe 35 contacted with the transparent electrodes3 on the substrate 1 and thus the preparation for voltage application tothe conductive frame 34 and to the transparent electrodes 3 on thesubstrate 1 was completed. Then, a voltage of +1 kV was graduallyapplied to the conductive frame 34 and to the transparent electrodes 3on the substrate 1. (Sudden application of a high voltage is undesirablesince such a trouble as dielectric breakdown of the transparentelectrodes 3 may be caused.)

Since, on that occasion, the conductive stage 15 was earthed, as shownin FIG. 64, and the substrate 1 was formed from an insulating material,the substrate 1 was attracted by and fixed on the conductive stage 15 bythe static electricity generated between the substrate 1 and conductivestage 15. If necessary, the substrate 1 may be positioned on apredetermined location on the conductive stage 15 by using positioningpins or the like.

And, spacers were charged positively and sprayed from the nozzle 11 a.As a result, as shown in FIG. 68, the spacers were sprayedconcentratedly into the gaps between transparent electrodes 3 and thegaps between the conductive frame 34 and transparent electrodes 3.

The voltage being applied to the substrate 1 with the spacers disposedthereon in the above manner only in the electrode gaps and the gapsbetween the conductive frame 34 and electrodes 3 was gradually loweredagain, and the substrate 1 was taken out to a finished goods stock siteby the robot mechanism 32 (this time, the procedure of feeding thesubstrate 1 was reversed).

INDUSTRIAL APPLICABILITY

The method of spraying particles according to the present invention,which is constituted as mentioned above, makes it possible to dispose apredetermined quantity of particles in desired positions, to disposespacers in electrode gaps in liquid crystal display devices withoutsacrificing the aperture ratio and, further, to properly dispose spacersin electrode gaps in the peripheral region of the display area as wellby applying a voltage to an electrode or electrodes outside the displayarea.

The method of liquid crystal display production according to theinvention, which is constituted as mentioned above, makes it possible,in conducting the method for producing a liquid crystal display devicecomprising disposing charged spacers in electrode gaps while applying avoltage to the transparent electrodes, to dispose spacers selectivelyonly in predetermined transparent electrode gaps among neighboringtransparent electrode gaps, namely at black matrix sites, even in thecase of stripe-shaped transparent electrodes such as employed in STNtype liquid crystal display devices, and to control the spacerdisposition density in the vicinity of the peripheral portions of thedisplay area as well as in the middle part of the display area, wherebyit becomes possible to make the spacer disposition density uniformwithin the display area and thus provide liquid crystal display devicesimproved in contrast while preventing light leakage through spacers,without sacrificing the aperture ratio.

Further, since spacers can be disposed all over the substrate, theliquid crystal display device produced therefrom can have a uniform cellthickness and high quality display performance characteristics withoutdisplay unevenness. Furthermore, spacers can be sprayed at predeterminedsites other than electrode sites without the need of providing, outsidethe display area, a dummy electrode or electrodes sufficiently largerthan the area of spacer spraying.

Furthermore, the liquid crystal display device according to theinvention, which is constituted as mentioned above, has a uniform cellthickness and high quality display performance characteristics withoutdisplay unevenness.

What is claimed is:
 1. A method of spraying particles which comprisesapplying a voltage of the same polarity as the particle charge polarityto a plurality of electrodes formed on a substrate and spraying theparticles while utilizing a repulsive force operating on the particles,wherein means is employed for preventing said particles from beingturned out of the electrode domain comprising the plurality ofelectrodes.
 2. The method of spraying particles according to claim 1,which comprises providing at least one dummy electrode outside theelectrode domain comprising the plurality of electrodes, and applying,to said dummy electrode, a voltage of the same polarity as the particlecharge polarity to thereby control the electric field above theperipheral region of the electrode domain comprising said plurality ofelectrodes.
 3. The method of spraying particles according to claim 1,wherein the voltage applied to the plurality of electrodes is 500 to8,000 V.
 4. The method of spraying particles according to claim 1,wherein a voltage having the same polarity as the particle chargepolarity is applied to at least one electrode other than said pluralityof electrodes, on the substrate in a region at least partly surroundingthe periphery of the electrode domain comprising the plurality ofelectrodes.
 5. The method of spraying particles according to claim 1wherein an electrode other than the plurality of electrodes is disposedin a region surrounding the periphery of the electrode domain other thanan accessory electrode for voltage application to said plurality ofelectrodes.
 6. The method of spraying particles according to claim 1wherein the area of an electrode other than the plurality of electrodesis larger than the area of any of said plurality of electrodes.
 7. Themethod of spraying particles according to claim 1 wherein the voltageapplied to an electrode other than the plurality of electrodes is thesame as that applied to said plurality of electrodes.
 8. The method ofspraying particles according to claim 4, wherein the electrode otherthan the plurality of electrodes is a solid electrode provided in theperiphery region of the substrate.
 9. The method of spraying particlesaccording to claim 1, wherein the particles are sprayed by dry method.